FIFTH SUPPLEMENTAL INDENTURE

Exhibit 4.2

ONEOK PARTNERS, L.P.

Issuer

ONEOK PARTNERS INTERMEDIATE LIMITED PARTNERSHIP

Guarantor

and

WELLS FARGO BANK, N.A.

Trustee

FIFTH SUPPLEMENTAL INDENTURE

Dated as of March 3, 2009

to

INDENTURE

relating to Senior Debt Securities

Dated as of September 25, 2006

8.625% Senior Notes due 2019

TABLE OF CONTENTS

EXHIBITS

Exhibit A: Form of Note

FIFTH SUPPLEMENTAL INDENTURE , dated as of March 3, 2009 (this “ Supplemental Indenture ”), among ONEOK P ARTNERS , L.P. , a Delaware limited partnership (the “ Partnership ”), ONEOK P ARTNERS I NTERMEDIATE L IMITED P ARTNERSHIP , a Delaware limited partnership (the “ Guarantor ”), and W ELLS F ARGO B ANK , N.A. , as trustee under the Indenture referred to below (in such capacity, the “ Trustee ”).

RECITALS OF THE PARTNERSHIP

WHEREAS, the Partnership and the Trustee have heretofore entered into an Indenture, dated as of September 25, 2006 (the “ Original Indenture ”) (the Original Indenture, as amended and supplemented from time to time, including without limitation pursuant to this Supplemental Indenture, being referred to herein as the “ Indenture ”); and

WHEREAS, under the Original Indenture, a new series of Debt Securities may at any time be established by the Board of Directors of ONEOK Partners GP, L.L.C., the Partnership’s general partner (the “ General Partner ”), in accordance with the provisions of the Original Indenture, and the terms of such series may be established by an indenture supplemental to the Original Indenture; and

WHEREAS, the Partnership proposes to create under the Indenture a new series of Debt Securities; and

WHEREAS, all acts and things necessary to make the Notes (as herein defined), when executed by the General Partner on behalf of the Partnership and authenticated and delivered by the Trustee as provided in the Original Indenture and this Supplemental Indenture, and the Guarantee, when executed by the general partner of the Guarantor on behalf of the Guarantor, the valid and binding obligations of the Partnership and the Guarantor and to make this Supplemental Indenture a valid and binding agreement in accordance with the Original Indenture have been done or performed;

NOW, THEREFORE, in consideration of the premises, agreements and obligations set forth herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree, for the equal and proportionate benefit of all Holders of the Notes, as follows:

ARTICLE 1

R ELATION TO I NDENTURE ; D EFINITIONS

SECTION 1.01. Relation to Indenture.

With respect to the Notes, this Supplemental Indenture constitutes an integral part of the Indenture.

SECTION 1.02. Definitions.

For all purposes of this Supplemental Indenture, capitalized terms used herein and not otherwise defined herein shall have the meanings assigned thereto in the Original Indenture.

SECTION 1.03. General References.

All references in this Supplemental Indenture to Articles and Sections, unless otherwise specified, refer to the corresponding Articles and Sections of this Supplemental Indenture; and the term “ herein ”, “ hereof ”, “ hereunder ” and any other word of similar import refers to this Supplemental Indenture.

ARTICLE 2

T HE S ERIES OF D EBT S ECURITIES

SECTION 2.01. The Form and Title of the Debt Securities.

There is hereby established a new series of Debt Securities to be issued under the Indenture and to be designated as the Partnership’s 8.625% Senior Notes due 2019 (the “ Notes ”). The Notes shall be substantially in the form attached as Exhibit A hereto, in each case with such appropriate insertions, omissions, substitutions and other variations as are required or permitted by the Indenture, and may have such letters, numbers or other marks of identification and such legends or endorsements placed thereon as the Partnership may deem appropriate or as may be required or appropriate to comply with any laws or with any rules made pursuant thereto or with the rules of any securities exchange or automated quotation system on which the Notes may be listed or traded, or to conform to general usage, or as may, consistently with the Indenture, be determined by the officers executing such Notes, as evidenced by their execution thereof.

The Notes shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to, the terms, conditions and covenants of the Original Indenture as supplemented by this Supplemental Indenture (including the form of Note set forth as Exhibit A hereto (the terms of which are incorporated in and made a part of this Supplemental Indenture for all intents and purposes)).

SECTION 2.02. Amount.

The aggregate principal amount of the Notes which may be authenticated and delivered pursuant hereto is unlimited. The Trustee shall initially authenticate and deliver Notes for original issue in an initial aggregate principal amount of up to $500,000,000 upon delivery to the Trustee of a Partnership Order for the authentication and delivery of such Notes. The aggregate principal amount of the Notes to be issued hereunder may be increased at any time hereafter and the series may be reopened for issuances of additional Notes upon Partnership Order without the consent of any Holder. The Notes issued on the date hereof and any such additional Notes that may be issued hereafter shall be part of the same series of Debt Securities for all purposes under the Indenture.

SECTION 2.03. Stated Maturity.

The Notes may be issued on any Business Day on or after March 3, 2009, and the Stated Maturity of the Notes shall be March 1, 2019.

SECTION 2.04. Interest and Interest Rates.

The rate or rates at which the Notes shall bear interest, the date or dates from which such interest shall accrue, the interest payment dates on which any such interest shall be payable and the regular record date for any interest payable on any interest payment date, in each case, shall be as set forth in the form of Note set forth as Exhibit A hereto.

SECTION 2.05. Optional Redemption.

At its option, the Partnership may redeem the Notes, in whole or in part, in principal amounts of $2,000 and in multiples of $1,000 in excess thereof, at any time or from time to time, at the applicable redemption price determined as set forth in the form of Note attached hereto as Exhibit A , in accordance with the terms set forth in the Notes and in accordance with Article III of the Original Indenture.

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SECTION 2.06. Guarantee .

Except as provided below, Article XII of the Original Indenture shall apply to the Notes. For the purposes of this Supplemental Indenture and the Notes (including without limitation the provisions of the Original Indenture to the extent applicable thereto), the term “ Guarantor ” shall mean ONEOK Partners Intermediate Limited Partnership, a Delaware limited partnership, and any successor Person thereto under the Indenture.

With respect to the Notes, paragraph (a) of Section 12.04 of the Original Indenture is hereby amended and restated in its entirety as set forth below; provided, however that the amendment and restatement set forth below in this Section 2.06 shall apply only to the Notes and not to any other series of Debt Securities issued under the Original Indenture:

“(a) Notwithstanding anything to the contrary in this Article XII, if any Guarantor shall cease to be a Subsidiary of the Partnership, then, if no Default or Event of Default shall have occurred and be continuing, such Guarantor, upon giving notice to the Trustee to the foregoing effect, shall be deemed to be released from all of its obligations under this Indenture, and the Guarantee shall be of no further force or effect with respect to such Guarantor. Following the receipt by the Trustee of any such notice, the Partnership shall cause this Indenture to be amended as provided in Section 9.01(l) hereof; provided, however , that the failure to so amend this Indenture shall not affect the validity of the termination of the Guarantee with respect to such Guarantor.”

The Guarantor’s address and telecopier number for the purposes of Section 13.03 of the Original Indenture is:

ONEOK Partners Intermediate Limited Partnership

100 West Fifth Street, Suite 1831

Tulsa, Oklahoma 74103-4298

Telecopier No.: (918) 588-7800

Attention: Chief Financial Officer

SECTION 2.07. Global Securities .

The Notes shall initially be issuable in whole or in part in the form of one or more Global Securities. Such Global Securities (i) shall be deposited with, or on behalf of, The Depository Trust Company, which shall act as Depositary with respect to the Notes, (ii) shall bear the legends applicable to Global Securities set forth in Section 2.15(a) of the Original Indenture, (iii) may be exchanged in whole or in part for Notes in definitive form upon the terms and subject to the conditions provided in Section 2.15(b) of the Original Indenture and in this Supplemental Indenture and (iv) shall otherwise be subject to the applicable provisions of the Indenture.

ARTICLE 3

M ISCELLANEOUS

SECTION 3.01. Certain Trustee Matters .

The recitals contained herein shall be taken as the statements of the Partnership, and the Trustee assumes no responsibility for their correctness.

The Trustee makes no representations as to the validity or sufficiency of this Supplemental Indenture, the Guarantee or the Notes or the proper authorization or the due execution hereof or thereof by the Partnership or the Guarantor.

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Except as expressly set forth herein, nothing in this Supplemental Indenture shall alter the duties, rights or obligations of the Trustee set forth in the Original Indenture.

The Trustee makes no representation or warranty as to the validity or sufficiency of the information contained in the prospectus supplement related to the Notes, except such information which specifically pertains to the Trustee itself, or any information incorporated therein by reference.

SECTION 3.02. Continued Effect .

Except as expressly supplemented and amended by this Supplemental Indenture, the Original Indenture shall continue in full force and effect in accordance with the provisions thereof, and the Original Indenture (as supplemented and amended by this Supplemental Indenture) is in all respects hereby ratified and confirmed. This Supplemental Indenture and all its provisions shall be deemed a part of the Original Indenture in the manner and to the extent herein and therein provided.

SECTION 3.03. Governing Law .

This Supplemental Indenture and the Notes shall be governed by and construed in accordance with the laws of the State of New York.

SECTION 3.04. Counterparts .

This instrument may be executed in any number of counterparts, each of which, when delivered, shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

(Signature Page Follows)

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IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed and delivered, all as of the day and year first above written.

Fifth Supplemental Indenture Signature Page

EXHIBIT A

[FORM OF FACE OF NOTE]

[If a Global Security, insert—UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”), NEW YORK, NEW YORK, TO THE PARTNERSHIP OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO., OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.]

[If a Global Security, insert—TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR’S NOMINEE, AND TRANSFERS OF PORTIONS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE INDENTURE REFERRED TO HEREIN.]

ONEOK PARTNERS, L.P.

8.625% Senior Note due 2019

ONEOK PARTNERS, L.P., a Delaware limited partnership (herein called the “Partnership”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to                                         , or registered assigns, the principal sum of