KOPPERS INC. SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN II

Exhibit 10.52

KOPPERS INC.

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN II

Amended and Restated as of

January 1, 2009

TABLE OF CONTENTS

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TABLE OF CONTENTS

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KOPPERS INC.

SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN II

PREAMBLE

Koppers Inc. (the “Company”) recognizes that the Internal Revenue Service limitations on compensation that may be taken into account for purposes of determining retirement benefits under a retirement plan qualified under Section 401(a) of the Internal Revenue Code may prevent some key employees from realizing sufficient benefits from the Company’s qualified retirement plan. The purpose of the Koppers Inc. Supplemental Executive Retirement Plan II (formerly named the Koppers Industries, Inc. Supplemental Executive Retirement Plan II) is to acknowledge and reward certain key employees of the Company for their efforts on behalf of the Company by providing additional post employment income to such key employees in order to facilitate their attainment of adequate levels of retirement income.

ARTICLE I

GENERAL

Section 1.1 Effective Date; Grandfathered Benefits . The original effective date of the Plan was December 1, 1997. The Plan, as hereby amended and restated, shall be effective as of January 1, 2009. The Plan as amended and restated applies only to a Participant’s Retirement Benefit that accrued on or after January 1, 2005, or Retirement Benefit that accrued prior to that date but was not fully vested on December 31, 2004. The Plan preceding this amendment and restatement applies to any Retirement Benefit that accrued and was vested prior to January 1, 2005 (“Grandfathered Benefits”); provided that any increase in the value of any subsidy with respect to Grandfathered Benefits payable upon retirement prior to the Retirement Plan’s Normal Retirement Date that accrues or increases as the result of service after December 31, 2004, shall not be treated as Grandfathered Benefits. The rights, if any, of any person whose status as an employee of an Employer has terminated shall be determined pursuant to the Plan as in effect on the date such employee terminated, unless a subsequently adopted provision of the Plan is made specifically applicable to such person.

Section 1.2 Intent . The Plan is intended to be an unfunded plan maintained primarily for the purpose of providing deferred compensation for a select group of management or highly compensated employees, as such group is described under Section 201(2), 301(a)(3), and 401(a)(1) of ERISA. Benefits provided under this Plan shall be funded solely from the general assets of the Employer and no participant or beneficiary hereunder shall have any interest or right to such assets.

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ARTICLE II

DEFINITIONS AND USAGE

Section 2.1 Definitions . Wherever used in the Plan, the following words and phrases shall have the meaning set forth below unless the context plainly requires a different meaning:

“ Actuarial Equivalent ” means a benefit having the same actuarial value as the benefit it replaces, determined using the same assumptions and methods as are used for determining an actuarial equivalent benefit under the Retirement Plan.

“ Accumulated Service ” means Accumulated Service as defined in the Retirement Plan.

“ Administrator ” means the Pension Committee appointed by the Board, or such other person or persons as designated by the Board.

“ Board ” means the Board of Directors of the Company.

“ Change in Control ” means a change in the ownership or control of the Company, as defined in Section 6.1.

“ Code ” means the Internal Revenue Code of 1986, as amended from time to time. Any reference to a particular Code section shall include any provision which modifies, replaces or supersedes it.

“ Company ” means Koppers Inc and any successor entity, and any entity that acquires ownership or control of Koppers Inc. or any successor entity.

“ Disability ” or “ Disabled ” means a physical or mental condition of a Participant resulting from a bodily injury, disease, or mental disorder which renders him incapable of continuing in the employment of the Employer. Such Disability shall be determined by the Administrator, in its sole and complete discretion, based upon appropriate medical advice and examination, and taking into account the ability of the Participant to continue in his or her same or similar, position with the Employer.

“ Early Retirement Date ” means the date on which a Participant retires from employment with the Employer after becoming eligible for an early retirement benefit under the Salaried Plan thereunder by reason of having (1) reached the age of 60 and completed 25 years of Accumulated Service, or (2) reached the age of 55 and completed 10 years of Accumulated Service, or (3) in the case of a Participant who has been Involuntarily Terminated on or after January 1, 1998 (other than a Participant who has ceased to be an active employee performing his or her normal job function but who is accruing benefits pursuant to a severance arrangement or employment contract with the Company), completed 30 years of Accumulated Service.

“ Employer ” means the Company and any other entity related to the Company in a manner described in Sections 414(b), (c), (m) or (o) of the Code.

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“ ERISA ” means the Employee Retirement Income Security Act of 1974, as amended from time to time. Any reference to a particular ERISA section shall include any provision which modifies, replaces, or supersedes it.

“ Final Average Pay ” means, with respect to any Participant, the sum of the following amounts: (i) the highest monthly base salary (excluding bonuses and other variable payments) paid in his or her last sixty (60) calendar months of full-time employment with the Employer multiplied by twelve (12); provided , however , that if a Participant has fewer than sixty (60) calendar months of full-time employment with the Employer, there shall be used in this clause the average of his or her regular base salary (excluding bonuses and other variable payments) during all of his or her calendar months of full-time employment with the Employer; plus (ii) the average incentive payment made for the last five (5) years of employment.

“ Involuntarily Terminated ” means any termination of a Participant’s employment with an Employer by reason of the discharge, firing or other involuntary termination of the Participant’s employment by action of such Employer, other than a Termination for Cause (as determined in good faith by the Administrator).

“ Normal Form ” means the normal form of distribution of the Participant’s Retirement Plan Benefit (i.e., a single life annuity for an unmarried Participant or a joint and 50% survivor annuity for a married Participant).

“ Normal Retirement Age ” means the age 65, or such other age that is defined from time to time as the normal retirement age under the Retirement Plan.

“ Normal Retirement Date ” means the date on which a Participant attains the Normal Retirement Age.

“ Participant ” means an eligible employee of an Employer who is participating in the Plan in accordance with Section 3.2.

“ Plan ” means the Koppers Inc. Supplemental Executive Retirement Plan II, as set forth herein and as it may be amended from time to time.

“ Plan Year ” means the calendar year.

“ Qualified Plan ” means the Retirement Plan and any other defined benefit pension plan(s) (within the meaning of Section 414(j) of the Code) intended to be qualified under Section 401(a) of the Code adopted and maintained by the Employer that provides benefits to Participants in this Plan.

“ Qualified Plan Benefit ” means the annuity annual equivalent benefit, expressed in the form of the annuity payable to a Participant under Section 5.1 hereof, that can be derived from the Qualified Plan. The determination of such annuity annual equivalent benefit shall be made

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using the mortality table that is in effect at such time for the Retirement Plan, an interest rate equal to the interest rate used under FAS 87 for the Retirement Plan for the previous year, and a commencement age under the Qualified Plan that is the same age at which the Retirement Benefit is to commence hereunder, in accordance with procedures established by the Administrator.

“ Retirement Benefit ” means the benefit payable under this Plan, as determined under Article IV.

“ Retirement Plan ” means the Retirement Plan for Koppers Inc., as subsequently amended and restated from time to time hereafter.

“ Retirement Plan Benefit ” means the benefit payable to a Participant under the Retirement Plan.

“ Separation from Service ” means a Participant’s separation from service with the Employer within the meaning of Section 409A of the Code. A Separation from Service occurs when the facts and circumstances indicate that the Employer and the Participant reasonably anticipate that no further services would be performed after a certain date or that the level of services the Participant would perform after such date would permanently decrease to no more than 20% of the average level of services performed over the immediately preceding 36-month period (or, if shorter, the entire period of the Participant’s employment with the Employer).

“ Social Security Benefit ” means the annual benefit payable under the Social Security Act at the Participant’s Social Security Retirement Age, relating to Old-Age and Disability benefits, determined under the provisions of the Social Security Act in effect on the date of a Participant’s Separation from Service. The Social Security Benefit will be calculated assuming that a Participant will not receive any future income that would be treated as wages for purposes of such Act, except that in the case of any deferred vested Retirement Benefit payable under Section 4.3, the Social Security Benefit will be calculated assuming that the Participant will receive the maximum amount of future income that would be treated as wages for purposes of the Social Security Act from the date of his or her Separation from Service until the Social Security Retirement Age.

“ Social Security Normal Retirement Age ” means the age used as the retirement age under Section 216(1) of the Social Security Act, as amended.

“ Specified Employee ” has the meaning set forth in Section 1.409A-1(i) of the Treasury Regulations issued under Section 409A of the Code.

“ Termination for Cause ” means the termination of a Participant’s employment due to (a) the willful and continued failure by the Participant to substantially perform his or her duties of employment (other than any such failure resulting from incapacity due to physical or mental illness) or any such actual or anticipated failure after the issuance of a notice of termination, after a written demand for substantial performance is delivered to the Participant by the Board, which

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demand specifically identifies the manner in which the Board believes that the Participant has not substantially performed his or her duties, and the Participant is given a reasonable opportunity to remedy such identified failure to perform, or (b) the willful engaging by the Participant in conduct which is demonstrably and materially injurious to the Employer, monetarily or otherwise. For purposes of this definition, no act or failure to act, shall be deemed “willful” unless done, or omitted to be done, not in good faith and without reasonable belief that such action or omission was in the best interest of the Employer.

Notwithstanding the foregoing, a Participant shall not be considered to have been terminated for cause unless there is delivered to the Participant a copy of a resolution duly adopted by the affirmative vote of not less than three-quarters (3/4) of the entire membership of the Board at a meeting of the Board called and held for such purpose (after reasonable notice to the Participant and an opportunity for the Participant, with legal counsel, to be heard before the Board), finding that in the good faith opinion of the Board, the Participant was engaged in the type of conduct set forth above in this definition, which specifies particular details and examples of such conduct.

“ Years of Service ” means the total number of years of “credited service” (as defined in the Retirement Plan) credited to a Participant under the Retirement Plan. In no event shall more than thirty-five (35) years be credited to any Participant, regardless of his or her actual period of service with the Employer or the number of years of credited service accumulated by the Participant under the Retirement Plan. At the discretion of the Administrator, Participants may be granted additional Years of Service that relate to employment with another employer for purposes of determining Retirement Benefits under this Plan, upon such terms and conditions as the Administrator may require (which conditions may include, but not be limited to, completion of a period of future service with the Employer and reducing the Participant’s Retirement Benefit hereunder by the pension benefits provided by such other employer).

Section 2.2 Usage . Except where otherwise indicated by the context, any masculine terminology used herein shall also include the feminine and vice versa, and the definition of any term herein in the singular shall also include the plural and vice versa.

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ARTICLE III

ELIGIBILITY AND PARTICIPATION

Section 3.1 Eligibility . An employee of an Employer shall be eligible to participate in the Plan if he or she is (i) an elected corporate officer of the Employer and agrees to enter into a non-compete, non-solicitation confidentiality agreement or (ii) a senior manager of the Employer who has been selected for participation in this Plan and agrees to enter into a non-compete, non-solicitation confidentiality agreement and who is participating in the Retirement Plan; provided, however, that any such employee shall be eligible to participate only to the extent, and for the period, that he or she is a member of a select group of management or highly compensated employees, as such group is described under Sections 201(2), 301(a)(3), and 401(a)(1) of ERISA. The Board shall make all determinations of eligibility in its sole and absolute discretion.

Section 3.2 Participation . An employee who is eligible to participate in the Plan pursuant to Section 3.1 as an elected corporate officer of the Employer and who is participating in the Retirement Plan shall automatically become a Participant upon election to such office and the execution of a non-compete, non-solicitation confidentiality agreement. Each other employee who is eligible to participate in the Plan pursuant to Section 3.1 shall become a Participant at such time and for the period as he or she is designated as eligible by the Board or, if no such period is specified, until his or her participation ceases in accordance with the terms of the Plan.

Section 3.3 Plan Frozen . Notwithstanding the foregoing, no employee shall become eligible to participate in this Plan after December 31, 2006, and the Retirement Benefit of any Participant in the Plan as of December 31, 2006, was frozen on such date and will not thereafter increase.

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ARTICLE IV

RETIREMENT BENEFITS

Section 4.1 Normal Retirement Benefit .

(a) Eligibility and Commencement . Subject to Section 4.6(b), a Participant who retires from employment with the Employer on or after his or her Normal Retirement Date shall receive a Retirement Benefit, determined in accordance with Section 4.1(b), which shall commence to be paid after the Participant’s retirement from the Employer becomes effective. The time and form of payment of the Retirement Benefit shall be determined in accordance with Section 5.1.

(b) Amount . The Retirement Benefit for a Participant who retires on or after his or her Normal Retirement Date shall be an annual amount, payable in the form specified under Section 5.1 that is equal to the following: