Exhibit

You and Codexis, Inc. (the “Company”) are currently parties to an Employment Agreement, dated as of May 28, 2012 (the “Employment Agreement”), which sets forth the terms of your employment with the Company and provides, among other things, that you will be entitled to receive certain severance payments and benefits upon certain qualifying terminations of employment with the Company. Effective as of the date of this Amendment, you and the Company hereby agree to amend (this “Amendment”) the Employment Agreement as follows:

“Measurement Date. ‘Measurement Date’, with respect to an award of performance stock units, shall mean the date the Compensation Committee of the Board of Directors determines the final performance factor for the applicable performance period.”

“provided that, any outstanding performance stock units held by Executive shall automatically become vested with respect to: (i) in the event of a Change of Control that occurs prior to the applicable Measurement Date, such number of shares of Company common stock corresponding to the target performance level for any applicable performance goals; or (ii) in the event of a Change of Control that occurs on or after the Measurement Date, such number of shares of Company common stock corresponding to the Company’s actual achievement of any applicable performance goals;”

All terms and provisions of the Employment Agreement not amended hereby, either expressly or by necessary implication, shall remain in full force and effect. From and after the date of this Amendment, all references to the term “Employment Agreement” in this Amendment or the original Employment Agreement shall include the terms contained in this Amendment.

Please indicate your acceptance of and agreement to the terms and conditions set forth in this Amendment by signing in the space below and returning the executed Amendment to the Company.