QuickLinks -- Click here to rapidly navigate through this document

Exhibit 32.2

Aquila, Inc.
Chief Financial Officer
Certification Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

        I, Rick J. Dobson, certify that:

1.

Aquila, Inc.'s annual report on Form 10-K for the annual period ending December 31, 2005 accompanying this Certification, in the form filed with the Securities and Exchange Commission (the "Report") fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934; and

2.

The information in the Report fairly presents, in all material respects, the financial condition and results of operations of Aquila, Inc.

Dated: March 6, 2006

/s/  RICK J. DOBSON Rick J. Dobson
Senior Vice President and Chief Financial Officer
Aquila, Inc.

QuickLinks

Aquila, Inc. Chief Financial Officer Certification Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002