EXHIBIT 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with this Quarterly Report (the “Report”) on Form 10-Q of Powell Industries, Inc. (the Company) for the quarter ended December 31, 2011, as filed with the Securities and Exchange Commission on the date hereof, I, Thomas W. Powell, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly represents, in all material respects, the financial condition and results of operations of the Company.

/s/ Thomas W. Powell

Thomas W. Powell

Chairman of the Board

President and Chief Executive Officer

Date: February 8, 2012