UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                              Washington, DC 20549

                                    FORM 8-K

                                 CURRENT REPORT
     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

                Date of Report (Date of earliest event reported):
                                  May 23, 2007

                           BOK FINANCIAL CORPORATION

             (Exact name of registrant as specified in its charter)



         Oklahoma                       000-19341              73-1373454
         --------                       ---------              ----------
(State or other jurisdiction           (Commission            (IRS Employer
     of incorporation)                 File Number)         Identification No.)


  Bank of Oklahoma Tower, Boston Avenue at Second Street, Tulsa, Oklahoma 74172
                    (Address of principal executive offices)

               Registrant's telephone number, including area code:
                                 (918) 588-6000

                                       N/A
          (Former name or former address, if changes since last report)

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

|_| Written communications pursuant to Rule 425 under the Securities Act (17 CFR
230.425).

|_| Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
240.14a-12).

|_| Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange
Act (17 CFR 240.14d-2(b)).

|_| Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange
Act (17 CFR 240.13e-4(c)).



                    INFORMATION TO BE INCLUDED IN THE REPORT


ITEM 1.01 - Entry Into a Material Definitive Agreement

     On May  23,  2007,  BOK  Financial  Corporation  ("BOKF")  entered  into an
agreement  to acquire all the issued and  outstanding  stock of United  Banks of
Colorado, Inc. ("UBC") for $43 million in cash (the "Stock Purchase Agreement").
First United Bank,  NA, a wholly owned  subsidiary of UBC, has $173.3 million in
assets and eleven banking locations in the Denver and Colorado Springs, Colorado
markets.  A copy of the press release announcing the Stock Purchase Agreement is
attached as Exhibit 99.1 and a copy of the Stock Purchase  Agreement is attached
as Exhibit 99.2.

     The  foregoing  description  of the  transaction  does  not  purport  to be
complete  and is  qualified  in its  entirety  by the Stock  Agreement  which is
incorporated herein by reference.  The Stock Agreement has been included in this
Current  Report  on  Form  8-K  to  provide   investors  and  stockholders  with
information regarding its terms. It is not intended to provide any other factual
information  about  UBC  or  its  subsidiaries.  The  Stock  Agreement  contains
representations  and  warranties  that the parties to the Stock  Agreement  made
solely  for  the  benefit  of  each  other.  The  assertions  embodied  in  such
representations  and  warranties  are  qualified by  information  contained in a
confidential  disclosure  schedule that UBC delivered in connection with signing
the Stock Agreement.


ITEM 9.01.  Financial Statements and Exhibits

         (d)      Exhibits

                    99.1 Text of press release dated May 23, 2007, BOK Financial
                         to Acquire First United Bank

                    99.2 Stock   Purchase    Agreement   Among   BOK   Financial
                         Corporation,  BOKF Stock  Corporation  Number Thirteen,
                         United Banks of Colorado,  Inc.,  First United Bank, NA
                         and Baltz Family Partners, Ltd. dated May 23, 2007


                                    Signature

Pursuant  to the  requirements  of the  Securities  Exchange  Act of  1934,  the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned hereunto duly authorized.


                            BOK FINANCIAL CORPORATION


                            By:  /s/  Steven E. Nell
                                --------------------------------
                                Steven E. Nell
                                Executive Vice President
                                Chief Financial Officer

Date:  May 23, 2007