FIFTY-FOURTH SUPPLEMENTAL INDENTURE

Exhibit 4 (b)

KANSAS GAS AND ELECTRIC COMPANY

TO

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.

(successor to BNY Midwest Trust Company)

and

JUDITH L. BARTOLINI

(successor to W. A. Spooner, Henry A. Theis, Oliver R. Brooks,

Wesley L. Baker, Edwin F. McMichael and R. Amundsen)

as Trustees under Kansas Gas and Electric Company’s

Mortgage and Deed of Trust, Dated as of April 1, 1940

FIFTY-FOURTH SUPPLEMENTAL INDENTURE

Providing, among other things, for

First Mortgage Bonds, 6.70% Series due June 15, 2019

Dated as of June 11, 2009

FIFTY-FOURTH SUPPLEMENTAL INDENTURE

INDENTURE, dated as of June 11, 2009, between Kansas Gas and Electric Company, a corporation of the State of Kansas (formerly named KCA Corporation and successor by merger to Kansas Gas and Electric Company, a corporation of the State of Kansas, hereinafter sometimes called the “Company-Kansas”), whose post office address is 100 North Broadway Street, Suite 800, Wichita, Kansas 67201 (hereinafter sometimes called the “Company”), and The Bank of New York Mellon Trust Company, N.A., a national banking association, whose post office address is 2 North LaSalle Street, Suite 1020, Chicago, Illinois 60602 (successor to BNY Midwest Trust Company (the “Corporate Trustee”)), and Judith L. Bartolini (successor to W.A. Spooner, Henry A. Theis, Oliver R. Brooks, Wesley L. Baker, Edwin F. McMichael and R. Amundsen, and being hereinafter sometimes called the “Individual Trustee”), whose post office address is 2 North LaSalle Street, Suite 1020, Chicago, Illinois 60602 (the Corporate Trustee and the Individual Trustee being hereinafter together sometimes called the “Trustees”), as Trustees under the Mortgage and Deed of Trust together with any indenture supplemental thereto (including this Indenture (hereinafter sometimes called the “Fifty-fourth Supplemental Indenture”)), dated as of April 1, 1940 (hereinafter called the “Mortgage”), which Mortgage was originally executed and delivered by Kansas Gas and Electric Company, a corporation of the State of West Virginia to which the Company-Kansas was successor by merger (hereinafter sometimes called the “Company-West Virginia”), to secure the payment of bonds issued or to be issued under and in accordance with the provisions of the Mortgage;

WHEREAS, the Company-West Virginia caused the Mortgage to be filed for record as a mortgage of real property and as a chattel mortgage in the offices of the Registers of Deeds in various counties in the State of Kansas, and on April 25, 1940 paid to the Register of Deeds of Sedgwick County, Kansas, that being the County in which the Mortgage was first filed for record, the sum of $40,000 in payment of the Kansas mortgage registration tax as provided by Section 79-3101 et seq. , General Statutes of Kansas 1935; and

WHEREAS, by the Mortgage, the Company-West Virginia covenanted that it would execute and deliver such supplemental indenture or indentures and such further instruments and do such further acts as might be necessary or proper to carry out more effectually the purposes of the Mortgage and to make subject to the lien of the Mortgage any property thereafter acquired, intended to be subject to the lien thereof; and

WHEREAS, an instrument, dated May 31, 1949, was executed by the Company-West Virginia appointing Oliver R. Brooks as Individual Trustee in succession to said Henry A. Theis, resigned, under the Mortgage, and by Oliver R. Brooks accepting the appointment as Individual Trustee under the Mortgage in succession to said Henry A. Theis, which instrument was filed for record in the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, an instrument, dated March 3, 1958, was executed by the Company-West Virginia appointing Wesley L. Baker as Individual Trustee in succession to said Oliver R. Brooks, resigned, under the Mortgage, and by Wesley L. Baker accepting the appointment as Individual Trustee under the Mortgage in succession to said Oliver R. Brooks, which instrument was filed for record in the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, an instrument, dated November 20, 1969, was executed by the Company-West Virginia appointing Edwin F. McMichael as Individual Trustee in succession to said Wesley L. Baker, resigned, under the Mortgage, and by Edwin F. McMichael accepting the appointment as Individual Trustee under the Mortgage in succession to said Wesley L. Baker, which instrument was filed for record in the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, by the Twenty-seventh Supplemental Indenture mentioned below, the Company-Kansas, among other things, appointed R. Amundsen as Individual Trustee in succession to said Edwin F. McMichael, resigned, under the Mortgage, and by R. Amundsen accepting the appointment as Individual Trustee under the Mortgage in succession to said Edwin F. McMichael; and

WHEREAS, by the Thirty-second Supplemental Indenture mentioned below, the Company-Kansas, among other things, appointed W. A. Spooner as Individual Trustee in succession to said R. Amundsen, resigned, under the Mortgage, and by W. A. Spooner accepting the appointment as Individual Trustee under the Mortgage in succession to said R. Amundsen; and

WHEREAS, by the Fortieth Supplemental Indenture mentioned below, the Company-Kansas, among other things, appointed Judith L. Bartolini as Individual Trustee in succession to said W.A. Spooner resigned, under the Mortgage, and by Judith L. Bartolini accepting the appointment as Individual Trustee under the Mortgage in succession to said W.A. Spooner; and

WHEREAS, the Company-West Virginia executed and delivered to the Trustees a First Supplemental Indenture, dated as of June 1, 1942 (which supplemental indenture is hereinafter sometimes called the “First Supplemental Indenture”); and

WHEREAS, the Company-West Virginia caused the First Supplemental Indenture to be filed for record as a mortgage of real property and as a chattel mortgage in the offices of the Registers of Deeds in various counties in the State of Kansas, but paid no mortgage registration tax in connection with the recordation of the First Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-West Virginia executed and delivered to the Trustees the following supplemental indentures:

which supplemental indentures are hereinafter sometimes called the Second through Twelfth Supplemental Indentures, respectively; and

WHEREAS, the Company-West Virginia caused the Second through Eighth Supplemental Indentures to be filed for record as a mortgage of real property and as a chattel mortgage in the offices of the Registers of Deeds in various counties in the State of Kansas, and caused the Ninth through Twelfth Supplemental Indentures to be filed for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State of Kansas, and on the following dates paid to the Register of Deeds of Sedgwick County, Kansas, that being the County in which the Second through Twelfth Supplemental Indentures were first filed for record as a mortgage of real property, the following amounts:

such amounts being in payment of the Kansas mortgage registration tax as provided by the then currently applicable sections of the statutes of the State of Kansas in effect on those dates; and

WHEREAS, the Company-West Virginia was merged into the Company-Kansas on May 31, 1973; and

WHEREAS, in order to evidence the succession of the Company-Kansas to the Company-West Virginia and the assumption by the Company-Kansas of the covenants and conditions of the Company-West Virginia in the bonds and in the Mortgage contained, and to enable the Company-Kansas to have and exercise the powers and rights of the Company-West Virginia under the Mortgage in accordance with the terms thereof, the Company-Kansas executed and delivered to the Trustees a Thirteenth Supplemental Indenture, dated as of May 31, 1973 (which supplemental indenture is hereinafter sometimes called the “Thirteenth Supplemental Indenture”); and

WHEREAS, the Company-Kansas caused the Thirteenth Supplemental Indenture to be filed for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State of Kansas, but paid no mortgage registration tax in connection with the recordation of the Thirteenth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas executed and delivered to the Trustees the following supplemental indentures:

which supplemental indentures are hereinafter sometimes called the Fourteenth through Fifty-third Supplemental Indentures, respectively; and

WHEREAS, the Company-Kansas caused the Fourteenth Supplemental Indenture to be filed for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State of Kansas; and

WHEREAS, the Company-Kansas caused the Fifteenth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on December 10, 1975, Film 169, page 363), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on December 10, 1975 and indexed as No. 325,911); and

WHEREAS, the Company-Kansas caused the Sixteenth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 29, 1976, Film 211, page 363), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on September 29, 1976 and indexed as No. 363,835); and

WHEREAS, the Company-Kansas caused the Seventeenth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 16, 1977, Film 234, page 492), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on March 1, 1977 and indexed as No. 384,759); and

WHEREAS, the Company-Kansas caused the Eighteenth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 26, 1977, Film 246, page 655), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on May 26, 1977 and indexed as No. 394,573); and

WHEREAS, the Company-Kansas caused the Nineteenth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 31, 1977, Film 263, page 882), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on September 1, 1977 and indexed as No. 406,577); and

WHEREAS, the Company-Kansas caused the Twentieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 29, 1978, Film 297, pages 635-656), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on March 30, 1978 and indexed as No. 434,072); and

WHEREAS, the Company-Kansas caused the Twenty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on January 9, 1979, Film 345, page 648), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on January 10, 1979 and indexed as No. 470,851); and

WHEREAS, the Company-Kansas caused the Twenty-second Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on April 2, 1980, Film 413, page 1,468), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on April 3, 1980 and indexed as No. 533,415); and

WHEREAS, the Company-Kansas caused the Twenty-third Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on July 1, 1980, Film 425, page 1,003), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on July 2, 1980 and indexed as No. 546,185); and

WHEREAS, the Company-Kansas caused the Twenty-fourth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 28, 1980, Film 435, page 266), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on August 29, 1980 and indexed as No. 554,543); and

WHEREAS, the Company-Kansas caused the Twenty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 30, 1981, Film 483, page 1,512), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on June 30, 1981 and indexed as No. 601,270); and

WHEREAS, the Company-Kansas caused the Twenty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on December 30, 1981, Film 510, page 300), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on December 31, 1981 and indexed as No. 628,293); and

WHEREAS, the Company-Kansas caused the Twenty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 6, 1982, Film 526, page 1,141), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on May 7, 1982 and indexed as No. 650,115); and

WHEREAS, the Company-Kansas caused the Twenty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 22, 1984, Film 645, page 1,524), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on March 23, 1984 and indexed as No. 796,449); and

WHEREAS, the Company-Kansas caused the Twenty-ninth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 5, 1984, Film 681, page 763), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on September 6, 1984 and indexed as No. 852,425); and

WHEREAS, the Company-Kansas caused the Thirtieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 12, 1984, Film 682, page 1,087), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on September 13, 1984 and indexed as No. 854,284); and

WHEREAS, the Company-Kansas caused the Thirty-third Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 18, 1991, Film 1177, page 0876), and as a security agreement in the Office of Secretary of State of Kansas (filed on June 18, 1991 and indexed as No. 1,693,446); and

WHEREAS, the Company-Kansas caused the Fortieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 28, 2000, Film 2062, page 0053), and as a security agreement in the Office of Secretary of State of Kansas (filed on June 28, 2000, and indexed as No. 3756913); and

WHEREAS, the Company on the following dates paid to the Register of Deeds of Sedgwick County, Kansas, that being the County in which the Fourteenth through Thirtieth Supplemental Indentures, the Thirty-third Supplemental Indenture and the Fortieth Supplemental Indenture were first filed for record as a mortgage of real property, the following amounts:

such amounts being in payment of the Kansas mortgage registration tax as provided by the then currently applicable sections of the statutes of the State of Kansas in effect on those dates; and

WHEREAS, the Company-Kansas caused the Thirty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on February 1, 1985, Film 707, page 378), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on February 4, 1985 and indexed as No. 895,468), but paid no mortgage registration tax in connection with the recordation of the Thirty-first Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-second Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on April 16, 1986, Film 791, page 1,336), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on April 17, 1986 and indexed as No. 1,048,212), but paid no mortgage registration tax in connection with the recordation of the Thirty-second Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, in order to evidence the succession of the Company to the Company-Kansas and the assumption by the Company of the covenants and conditions of the Company-Kansas in the bonds and in the Mortgage contained, and to enable the Company to have and exercise the powers and rights of the Company-Kansas under the Mortgage in accordance with the terms thereof, the Company executed and delivered to the Trustees a Thirty-fourth Supplemental Indenture, dated as of March 31, 1992 (which supplemental indenture is hereinafter sometimes called the “Thirty-fourth Supplemental Indenture”); and

WHEREAS, the Company-Kansas caused the Thirty-fourth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 31, 1992, Film 1236, page 987), and as a security agreement in the Office of Secretary of State of Kansas (filed on March 31, 1992 and indexed as No. 1,780,893), but paid no mortgage registration tax in connection with the recordation of the Thirty-fourth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company caused the Thirty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on December 16, 1992, Film 1301, page 0104), and as a security agreement in the Office of Secretary of State of Kansas (filed on December 16, 1992 and indexed as No. 1,861,886), but paid no mortgage registration tax in connection with the recordation of the Thirty-fifth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 10, 1993, Film 1364, page 0515), and as a security agreement

in the Office of Secretary of State of Kansas (filed on August 11, 1993 and indexed as No. 1,936,501), but paid no mortgage registration tax in connection with the recordation of the Thirty-sixth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on January 18, 1994, Film 1411, page 0710), and as a security agreement in the Office of Secretary of State of Kansas (filed on January 18, 1994 and indexed as No. 1,985,104), but paid no mortgage registration tax in connection with the recordation of the Thirty-seventh Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on February 28, 1994, Film 1422, page 1046), and as a security agreement in the Office of Secretary of State of Kansas (filed on February 28, 1994 and indexed as No. 1,997,743), but paid no mortgage registration tax in connection with the recordation of the Thirty-eighth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-ninth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on April 27, 1994, Film 1440, page 855), and as a security agreement in the Office of Secretary of State of Kansas (filed on April 27, 1994 and indexed as No. 1,377,915), but paid no mortgage registration tax in connection with the recordation of the Thirty-ninth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 6, 2002, Film 2460, page 1), and as a security agreement in the office of Secretary of State of Kansas (filed on June 6, 2002, and indexed as No. 5264221), but paid no mortgage registration tax in connection with the recordation of the Forty-first Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-second Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 12, 2004, Film 2854, page 8731), and as a security agreement in the office of Secretary of State of Kansas (filed on March 12, 2004, and indexed as No. 5760673), but paid no mortgage registration tax in connection with the recordation of the Forty-second Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-third Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 10, 2004, Film and Page 28578510), and as a security agreement in the office of Secretary of State of Kansas (filed on June 10, 2004, and indexed as No. 5820311), but paid no mortgage registration tax in connection with the recordation of the Forty-third Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-fourth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 6, 2005, Film and Page 28671438), and as a security agreement in the office of Secretary of State of Kansas (filed on May 6, 2005, and indexed as No. 5981824), but paid no mortgage registration tax in connection with the recordation of the Forty-fourth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 17, 2006, Film and Page 28764552), and as a security agreement in the office of Secretary of State of Kansas (filed on March 17, 2006, and indexed as No. 6122576), but paid no mortgage registration tax in connection with the recordation of the Forty-fifth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 1, 2006, Film and Page 28785638, and as a security agreement in the office of Secretary of State of Kansas (filed on June 1, 2006, and indexed as No. 6168504), but paid no mortgage registration tax in connection with the recordation of the Forty-sixth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 16, 2007, Film and Page 28865277), and as a security agreement in the office of Secretary of State of Kansas (filed on March 16, 2007, and indexed as No. 6326219), but paid no mortgage registration tax in connection with the recordation of the Forty-seventh Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on July 13, 2007, Film and Page 28899558), and as a security agreement in the office of Secretary of State of Kansas (filed on July 13, 2007, and indexed as No. 6385835), but paid no mortgage registration tax in connection with the recordation of the Forty-eighth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-ninth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on October 12, 2007, Film and Page 28923805), and as a security agreement in the office of Secretary of State of Kansas (filed on October 12, 2007, and indexed as No. 6417307), but paid no mortgage registration tax in connection with the recordation of the Forty-ninth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fiftieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on February 22, 2008, Film and Page 28953801), and as a security agreement in the office of Secretary of State of Kansas (filed on February 25, 2008, and indexed as No. 6458236), but paid no mortgage registration tax in connection with the recordation of the Fiftieth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fifty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 15, 2008, Film and Page 28975775), and as a security agreement in the office of Secretary of State of Kansas (filed on May 15, 2008, and indexed as No. 6489843), but paid no mortgage registration tax in connection with the recordation of the Fiftieth-first Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fifty-second Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 26, 2008, Film and Page 29002339), and as a security agreement in the office of Secretary of State of Kansas (filed on August 26, 2008, and indexed as No. 6521686, and refiled on October 2, 2008, and indexed as No. 6533509), but paid no mortgage registration tax in connection with the recordation of the Fifty-second Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fifty-third Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on October 10, 2008, Film and Page 29013036), and as a security agreement in the office of Secretary of State of Kansas (filed on October 10, 2008, and indexed as No. 6535637), but paid no mortgage registration tax in connection with the recordation of the Fifty-third Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-West Virginia, the Company-Kansas or the Company has from time to time caused to be filed in the respective offices of the above-mentioned Registers of Deeds and Secretary of State affidavits executed by the Trustees under the Mortgage, preserving and continuing the lien thereof either as a chattel mortgage in accordance with the provisions of K.S.A. 58-303 (Section 58-303 of the General Statutes of Kansas 1935) or as a security agreement under the provisions of
K.S.A. 84-9-401 et seq.; and

WHEREAS, in addition to the aforesaid filings for record in the respective offices of the above-mentioned Registers of Deeds, the Company-West Virginia, the Company-Kansas or the Company has filed copies of the Mortgage and the First through Fiftieth-third Supplemental Indentures, certified as true by it, with the Secretary of State of Kansas; and

WHEREAS, the Company-West Virginia, the Company-Kansas or the Company has heretofore issued, in accordance with the provisions of the Mortgage, as heretofore supplemented, the following series of First Mortgage Bonds:

hereinafter sometimes called Bonds of the First through Fifty-ninth Series; and

WHEREAS, Section 8 of the Mortgage provides that the form of each series of bonds (other than the First Series) issued thereunder and of the coupons to be attached to the coupon bonds of such series shall be established by Resolution of the Board of Directors of the Company and that the form of such series, as established by said Board of Directors, shall specify the descriptive title of the bonds and various other terms thereof, and may also contain such provisions not inconsistent with the provisions of the Mortgage as the Board of Directors may, in its discretion, cause to be inserted therein expressing or referring to the terms and conditions upon which such bonds are to be issued and/or secured under the Mortgage; and

WHEREAS, Section 120 of the Mortgage provides, among other things, that any power, privilege or right expressly or impliedly reserved to or in any way conferred upon the Company by any provision of the Mortgage whether such power, privilege or right is in any way restricted or is unrestricted, may be in whole or in part waived or surrendered or subjected to any restriction if at the time unrestricted or to additional restriction if already restricted, and the Company may enter into any further covenants, limitations or restrictions for the benefit of any one or more series of bonds issued thereunder, or the Company may cure any ambiguity contained therein or in any supplemental indenture, or may establish the terms and provisions of

any series of bonds other than said First Series, by an instrument in writing executed and acknowledged by the Company in such manner as would be necessary to entitle a conveyance of real estate to record in all of the states in which any property at the time subject to the lien of the Mortgage shall be situated; and

WHEREAS, the Company now desires to create a new series of bonds; and

WHEREAS, the execution and delivery by the Company of this Fifty-fourth Supplemental Indenture, and the terms of the Bonds of the Sixtieth Series, hereinafter referred to, have been duly authorized by the Board of Directors of the Company by appropriate Resolutions of said Board of Directors;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That Kansas Gas and Electric Company, in consideration of the premises and of One Dollar ($1) to it duly paid by the Trustees at or before the ensealing and delivery of these presents, the receipt whereof is hereby acknowledged, and in further evidence of assurance of the estate, title and rights of the Trustees and in order further to secure the payment both of the principal of and interest and premium, if any, on the bonds from time to time issued under the Mortgage, according to their tenor and effect and the performance of all the provisions of the Mortgage (including any instruments supplemental thereto and any modification made as in the Mortgage provided) and of said bonds, hereby grants, bargains, sells, releases, conveys, assigns, transfers, mortgages, pledges, sets over and confirms (subject, however, to Excepted Encumbrances as defined in Section 6 of the Mortgage) unto The Bank of New York Mellon Trust Company, N.A. and to Judith L. Bartolini, as Trustees under the Mortgage, and to their successor or successors in said trust, and to said Trustees and their successors and assigns forever, all property, real, personal and mixed, acquired by the Company after the date of the execution and delivery of the Mortgage, in addition to property covered by the First through the Fifty-third Supplemental Indentures (except any herein or in the Mortgage, as heretofore supplemented, expressly excepted), now owned or, subject to the provisions of Section 87 of the Mortgage, hereafter acquired by the Company and wheresoever situated, including (without in anywise limiting or impairing by the enumeration of the same the scope and intent of the foregoing or of any general description contained in this Fifty-fourth Supplemental Indenture) all lands, flowage rights, water rights, flumes, raceways, dams, rights of way and roads; all steam and power houses, gas plants, street lighting systems, standards and other equipment incidental thereto, telephone, radio and television systems, air-conditioning systems and equipment incidental thereto, water works, steam heat and hot water plants, lines, service and supply systems, bridges, culverts, tracks, rolling stock, ice or refrigeration plants and equipment, street and interurban railway systems, offices, buildings and other structures and the equipment thereof; all machinery, engines, boilers, dynamos, electric and gas machines, regulators, meters, transformers, generators, motors, electrical, gas and mechanical appliances, conduits, cables, water, steam heat, gas or other pipes, gas mains and pipes, service pipes, fittings, valves and connections, pole and transmission lines, wires, cables, tools, implements, apparatus, furniture, chattels and chooses in action; all municipal and other franchises; all lines for the transmission and distribution of electric current, gas, steam heat or water for any purpose, including poles, wires, cables, pipes, conduits, ducts and all apparatus for use in connection therewith; all real estate, lands, easements, servitudes, licenses, permits, franchises, privileges, rights of way and

other rights in or relating to real estate or the occupancy of the same and (except as herein or in the Mortgage, as heretofore supplemented, expressly excepted), all the right, title and interest of the Company in and to all other property of any kind or nature appertaining to and/or used and/or occupied and/or enjoyed in connection with any property hereinbefore or in the Mortgage, as heretofore supplemented, described.

TOGETHER WITH all and singular the tenements, hereditarnents and appurtenances belonging or in anywise appertaining to the aforesaid property or any part thereof, with the reversion and reversions, remainder and remainders and (subject to the provisions of Section 57 of the Mortgage) the tolls, rents, revenues, issues, earnings, income, product and profits thereof, and all the estate, right, title and interest and claim whatsoever, at law as well as in equity, which the Company now has or may hereafter acquire in and to the aforesaid property and franchises and every part and parcel thereof.

IT IS HEREBY AGREED by the Company that, subject to the provisions of Section 87 of the Mortgage, all the property, rights and franchises acquired by the Company after the date hereof (except any herein or in the Mortgage, as heretofore supplemented, expressly excepted), shall be as fully embraced within the lien hereof and the lien of the Mortgage, as if such property, rights and franchises were now owned by the Company and were specifically described herein and conveyed hereby.

PROVIDED that the following are not and are not intended to be now or hereafter granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, pledged, set over or confirmed hereunder and are hereby expressly excepted from the lien and operation of this Fifty-fourth Supplemental Indenture and from the lien and operation of the Mortgage, viz.: (1) cash, shares of stock and obligations (including bonds, notes and other securities) not hereafter specifically pledged, paid, deposited or delivered under the Mortgage or covenanted so to be; (2) merchandise, equipment, materials or supplies held for the purpose of sale in the usual course of business and fuel, oil and similar materials and supplies consumable in the operation of any properties of the Company; vehicles and automobiles; (3) bills, notes and accounts receivable, and all contracts, leases and operating agreements not specifically pledged under the Mortgage or covenanted so to be; and (4) electric energy, and other materials or products generated, manufactured, produced or purchased by the Company for sale, distribution or use in the ordinary course of its business; provided, however, that the property and rights expressly excepted from the lien and operation of the Mortgage and this Fifty-fourth Supplemental Indenture in the above subdivisions (2) and (3) shall (to the extent permitted by law) cease to be so excepted in the event that either or both of the Trustees or a receiver or trustee shall enter upon and take possession of the Mortgaged and Pledged Property in the manner provided in Article XII of the Mortgage by reason of the occurrence of a Default as defined in said Article XII.

THERE is expressly excepted from the lien of the Mortgage and from the lien hereof all property of the Company located in the State of Missouri now owned or hereafter acquired unless such property in the State of Missouri shall be subjected to the lien of the Mortgage by an indenture or indentures supplemental thereto, pursuant to authorization by the Board of Directors of the Company.

TO HAVE AND TO HOLD all such properties, real, personal and mixed, granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, pledged, set over or confirmed by the Company as aforesaid, or intended so to be, unto the Trustees, their successors and assigns forever.

IN TRUST NEVERTHELESS, for the same purposes and upon the same terms, trusts and conditions and subject to and with the same provisos and covenants as are set forth in the Mortgage, as supplemented, this Fifty-fourth Supplemental Indenture being supplemental thereto.

AND IT IS HEREBY COVENANTED by the Company that all the terms, conditions, provisos, covenants and provisions contained in the Mortgage, as supplemented, shall affect and apply to the property hereinbefore described and conveyed and to the estate, rights, obligations and duties of the Company and Trustees and the beneficiaries of the trust with respect to said property, and to the Trustees and their successors as Trustees of said property in the same manner and with the same effect as if the said property had been owned by the Company at the time of the execution of the Mortgage, and had been specifically and at length described in and conveyed to the Trustees by the Mortgage as a part of the property therein stated to be conveyed.

The Company further covenants and agrees to and with the Trustees and their successors in said trust under the Mortgage, as follows:

ARTICLE I

SIXTIETH SERIES OF BONDS

SECTION 1. There shall be a series of bonds designated “6.70% Series due 2019” (herein sometimes referred to as the “ Bonds of the Sixtieth Series ”), each of which shall also bear the descriptive title, First Mortgage Bond, and the form thereof, which is established by Resolution of the Board of Directors of the Company, is attached hereto as Exhibit A. Bonds of the Sixtieth Series shall be limited to $300,000,000 in aggregate principal amount, except as provided in Section 16 of the Mortgage, shall mature on June 15, 2019, and shall be issued as fully registered bonds in denominations of Two Thousand Dollars and in any multiple or multiples of One Thousand Dollars in excess thereof. Bonds of the Sixtieth Series shall bear interest from the date of their issuance at the rate of 6.70% per annum, payable semi-annually on June 15 and December 15 of each year, beginning December 15, 2009, to holders of record on the preceding June 1 or December 1, as applicable, whether or not a business day. The principal of, redemption premium, if any, and interest on Bonds of the Sixtieth Series shall be payable at the office or agency of the Company in the Borough of Manhattan, The City of New York, in such coin or currency of the United States of America as at the time of payment is legal tender for public and private debts, except as follows. Payments in respect of the Bonds of the Sixtieth Series represented by Global Bonds (as defined be