AMENDMENT #2 TO EMPLOYMENT AGREEMENT

Exhibit 10.73

AMENDMENT #2 TO EMPLOYMENT AGREEMENT

This AMENDMENT #2 (the “Amendment”) is made as of the 19^th day of December, 2012, by and between Steven Lacy (“Executive”) and Koppers Inc. (the “Company”).

WHEREAS, Executive and the Company entered into an Employment Agreement setting forth the terms and conditions of Executive’s employment with the Company dated April 5, 2002 (the “Employment Agreement”);

WHEREAS, the parties entered into an amendment of the Employment Agreement to comply with applicable requirements under Section 409A of the Internal Revenue Code of 1986, as amended, and the final regulations and other interpretive guidance issued thereunder (“Section 409A”), which amendment was effective as of January 1, 2009; and

WHEREAS, the parties desire to further amend the Employment Agreement to clarify its continued compliance with Section 409A.

NOW THEREFORE, the parties, intending to be legally bound, hereby agree as follows:

“The salary continuation benefits payable under this subsection (ii) shall begin as soon as possible following Executive’s execution of the release set forth in Section 8(d) and the expiration of the revocation period for the release, but in no event later than sixty (60) days following Executive’s termination of employment, subject to the provisions of Section 8(d).”

“(d) Release. Payment of the sums set forth in Sections 8(c)(ii) and (iii) and provision of the benefits set forth in Section 8(c)(iv) to Executive shall be conditioned upon Executive executing and delivering a release satisfactory to the Company, and, notwithstanding subsection (e), shall not be made or provided until Executive executes and delivers the release and the revocation period for the release has expired, which release shall release the Company and affiliated companies and persons from any and all claims, demands, damages, actions and/or causes of action whatsoever, which he may have had on account of the termination of his employment, including, but not limited to claims of discrimination, including on the basis of sex, race, age, national origin, religion, or handicapped status (with all applicable periods during which Executive may revoke the release or any provision thereof having expired), and any and all claims, demands and causes of action under any retirement or welfare benefit plan of the Company (as defined in the Employee Retirement Income Security Act of 1974, as amended), other than under the Company’s 401(k) plan and the Qualified Plan (as hereinafter defined), severance or other termination pay. Such release shall not, however, apply to the ongoing obligations of the Company arising under this Agreement, or any rights of indemnification Executive may have under the Company’s policies or by contract or by statute.

Notwithstanding anything to the contrary in this Agreement, in the case of any severance benefits payable under Sections 8(c)(ii) and (iii) or provided under Section 8(c)(iv) that are or may be deferred compensation subject to Internal Revenue Code Section 409A (as defined in Section 20) and are subject to an effective release as set forth above, where the period for execution and non-revocation of a release spans more than one calendar year, no such payment or benefit shall be made or provided any earlier than the beginning of the second calendar year. In no event may Executive, directly or indirectly, designate the calendar year of payment.”

“The lump-sum amount payable under this paragraph (iv) shall be paid as soon as possible following Executive’s execution of the release set forth in Section 9(g) and the expiration of the revocation period for the release, but in no event later than sixty (60) days following Executive’s termination of employment, subject to the provisions of Section 9(g).”

“(g) Executive’s entitlement to the payments and benefits set forth in Sections 9(c)(ii), (iii), (iv), (v) and (vi) shall be conditioned upon Executive executing and delivering a release satisfactory to the Company, and, notwithstanding subsection (d), shall not be made or provided until Executive executes and delivers the release and the revocation period for the release has expired, which release shall release the Company and affiliated companies and persons from any and all claims, demands, damages, actions and/or causes of action whatsoever, which he may have had on account of the termination of his employment, including, but not limited to claims of discrimination, including on the basis of sex, race, age, national origin, religion, or handicapped status (with all applicable periods during which Executive may revoke the release or any provision thereof having expired), and any and all claims, demands and causes of action under any retirement or welfare benefit plan of the Company (as defined in the Employee Retirement Income Security Act of 1974, as amended), other than under the Company’s 401(k) plan and the Qualified Plan, severance or other termination pay. Such release shall not, however, apply to the ongoing obligations of the Company arising under this Agreement, or any rights of indemnification Executive may have under the Company’s policies or by contract or by statute.

Notwithstanding anything to the contrary in this Agreement, in the case of any payments or benefits set forth in Sections 9(c)(ii), (iii), (iv), (v) and (vi) that are or may be deferred compensation subject to Section 409A (as defined in Section 20) and are subject to an effective release as set forth above, where the period for execution and non-revocation of a release spans more than one calendar year, no such payment or benefit shall be made or provided any earlier than the beginning of the second calendar year. In no event may Executive, directly or indirectly, designate the calendar year of payment.”

“(d) In the event that Executive qualifies for benefits under Section 9 of this Agreement as the result of either (i) a termination prior to the date of a Change in Control, as provided under Section 9(b)(ii) or (ii) a termination following a Change in Control that would not also be deemed a ‘change in the ownership of the Company,’ a ‘change in the effective control of the Company,’ or a ‘change in the ownership of a substantial portion of the Company’s assets’ under Section 409A, then notwithstanding any other provision of Section 9, any portion of the benefit payable under Section 9 that is (i) subject to Section 409A and (ii) equals the amount of benefit Executive would have been eligible to receive under Section 8 if such termination were not in connection with a Change in Control, shall be paid at the same time and in the same form as provided under Section 8, with the remaining amount of such benefit payable as otherwise provided under Section 9.”

IN WITNESS WHEREOF, the parties hereto have executed and delivered this Amendment as of the day and year first above written.