UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K /A

Amendment No. 1

For the fiscal year ended December 31, 2011

or

Commission file number 001-34581

KRATON PERFORMANCE POLYMERS, INC.

(Exact Name of Registrant as Specified in its Charter)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    YES  x    NO  ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    YES  ¨    NO  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    YES  x    NO  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    YES  x    NO  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.    ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See definitions of “large accelerated filer”, “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Securities Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).    YES  ¨    NO  x

Estimated aggregate market value of the common equity held by nonaffiliates of Kraton Performance Polymers, Inc. at June 30, 2011: $1,249,068,040. Number of shares of Kraton Performance Polymers, Inc. Common Stock, $0.01 par value, outstanding at February 24, 2012: 32,103,523.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of Kraton Performance Polymers, Inc.’s proxy statement for the 2012 Annual Meeting of Shareholders are incorporated by reference in Part III.

EXPLANATORY NOTE

We are filing this Amendment No. 1 (the “Amendment”) to our Annual Report on Form 10-K for the year ended December 31, 2011, which was filed with the U.S. Securities and Exchange Commission (the “SEC”) on February 29, 2012 (the “Original 10-K”). The sole purpose of the Amendment is to update the incorporation by reference information for Exhibit 10.5.

As required by Rule 12b-15 of the Securities Exchange Act of 1934, as amended, new certifications by our principal executive officer and principal financial officer are filed herewith as exhibits to the Amendment. Except as described above, the Amendment does not reflect events occurring after the date of the Original 10-K or modify or update the disclosures in the Original 10-K.

PART IV

(a) 2. Exhibits

The exhibits listed on the accompanying Exhibit Index are filed as part of this Amendment No. 1 on Form 10-K/A or incorporated herein by reference.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: March 8, 2012

EXHIBIT INDEX

The following is a list of all exhibits filed as a part of this Amendment No. 1 on Form 10-K/A, including those incorporated herein by reference.