Exhibit 32.2
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                           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 Quarterly Report of Zoltek Companies, Inc. (the
"Company") on Form 10-Q for the period ending March 31, 2007 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Kevin
Schott, Chief Financial 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, to the best of my knowledge and belief, 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.

Date:  May 10, 2007                              By:   /s/ KEVIN SCHOTT
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                                                           Kevin Schott
                                                     Chief Financial Officer