FCStone (FCSX) 10-Q 2008 Q3 Quarterly report

Exhibit 32.2

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 FCStone Group, Inc. (the “Company”) on Form 10-Q for the fiscal 2nd Quarter 2008 ending February 29, 2008, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, William J. Dunaway, 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, that, to the best of my knowledge and belief:

(1) the Report fully complies with the requirements of Section 13(a) or 15(b) 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 result of operations of the Company.

/s/ William J. Dunaway

William J. Dunaway

Chief Financial Officer

(Principal Financial Officer)

July 15, 2008

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.