CECO Environmental (CECO) 10-K 2011 FY Annual report

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 the Annual Report of CECO Environmental Corp. (the “Company”) on Form 10-K for the period ending December 31, 2011, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Jeffrey Lang, 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 presents, in all material respects, the financial condition and results of operations of the Company.

/s/ JEFFREY LANG

Jeffrey Lang

Chief Executive Officer

March 16, 2012