EXHIBIT 32.1


The following certification is provided by the undersigned President and
Principal Executive Officer of UnionBancorp, Inc. on the basis of such officer's
knowledge and belief for the sole purpose of complying with 18 U.S.C. Section
1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

                                  CERTIFICATION
                                  -------------

In connection with the Annual Report of UnionBancorp, Inc. (the "Company") on
Form 10-K for the period ended December 31, 2005 as filed with the Securities
and Exchange Commission on March 24, 2006 (the "Report"), I, Scott A. Yeoman,
President and Principal Executive Officer of the Company, hereby 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)
               of the Securities Exchange Act of 1934, as amended; 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/ SCOTT A. YEOMAN
                               ------------------------------------------------
                               Name: Scott A. Yeoman
                               Title: President and Principal Executive Officer
                               Date: March 24, 2006