UNITED STATES                    SEC File Number
                      SECURITIES AND EXCHANGE COMMISSION            001-12515
                            Washington, D.C. 20549
                                                                   Cusip Number
                                 FORM 12b-25                          

                          NOTIFICATION OF LATE FILING

(Check One) [ ] Form 10-K __ Form 20-F __ Form 11-K [X] Form 10-Q __ Form N-SAR

                 For Period Ended: June 30, 2005
                 [  ]     Transition Report on Form 10-K
                 [  ]     Transition Report on Form 20-F
                 [  ]     Transition Report on Form 11-K
                 [  ]     Transition Report on Form 10-Q
                 [  ]     Transition Report on Form N-SAR
                 For the Transition Period Ended:____________________________

 READ ATTACHED INSTRUCTION SHEET BEFORE PREPARING FORM.  PLEASE PRINT OR TYPE

   Nothing in the form shall be construed to imply that the Commission has
                  verified any information contained herein.
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    If the notification relates to a portion of the filing checked above,
           identify the Item(s) to which the notification relates:
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PART I - REGISTRANT INFORMATION

OM Group, Inc.
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Full Name of Registrant


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Former Name if Applicable

127 Public Square, 1500 Key Tower
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Address of Principal Executive Office (STREET AND NUMBER)

Cleveland, OH 44114-1221
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City, State and Zip Code


PART II - RULES 12b-25(b) and (c)

If the subject report could not be filed without unreasonable effort or expense
and the registrant seeks relief pursuant to Rule 12b-25(b), the following
should be completed.  (Check appropriate box)

 X       (a)     The reasons described in reasonable detail in Part III of this
                 form could not be eliminated without unreasonable effort or
                 expense;

__       (b)     The subject annual report, semi-annual report, transition
                 report on Form 10-K, Form 20-F, 11-K, Form N-SAR, or portion
                 thereof, will be filed on or before the fifteenth calendar day
                 following the prescribed due date; or the subject quarterly
                 report of transition report on Form 10-Q, or portion thereof
                 will be filed on or before the fifth calendar day following
                 the prescribed due date; and

 __      (c)     The accountant's statement or other exhibit required by Rule
                 12b-25(c) has been attached if applicable.

PART III - NARRATIVE

State below in reasonable detail the reasons why the Form 10-K, 11-K, 20-F,
10-Q,   N-SAR, or the transition report or portion thereof, could not be filed
within the prescribed time period.  

The Company completed and filed its 2003 Form 10-K, which contained restated
financial statements for 2002 and 2001 and restated financial information for
2000 and 1999, on March 31, 2005. The Company filed its Form 10-Q's for 2004 on
June 10, 2005. The Company is currently working to complete and file its Form
10-K for 2004.

As a result, the Company is unable to file its Form 10-Q for the period ended
June 30, 2005 by the prescribed due date. The Company intends to complete its
2004 Form 10-K and first and second quarter 2005 Form 10-Q's as promptly as is
practicable, but does not expect the filing of the second quarter 2005 Form 10-Q
to be made by August 15, 2005.


PART IV - OTHER INFORMATION

(1)      Name and telephone number of person to contact in regard to this
         notification

         R. Louis Schneeberger             216                 781-0083
         --------------------------     -----------        ------------------
                  (Name)                (Area Code)        (Telephone Number)

(2)      Have all other periodic reports required under Section 13 or 15(d) of
         the Securities Exchange Act of 1934 or Section 30 of the Investment
         Company Act of 1940 during the preceding 12 months or for such shorter
         period that the registrant was required to file such reports been
         filed?  If answer is no identify report(s).
         __  Yes   X  No

         Form 10-K - Year ended December 31, 2004
         Form 10-Q - Quarter ended March 31, 2005

(3)      Is it anticipated that any significant change in results of operations
         from the corresponding period for the last fiscal year will be
         reflected by the earnings statements to be included in the subject
         report or portion thereof?    X  Yes   __ No

         If so, attach an explanation of the anticipated change, both
         narratively and quantitatively, and, if appropriate, state the reasons
         why a reasonable estimate of the results cannot be made:

         The results for the quarter ended June 30, 2005 are expected to be
         significantly different from those to be reported for 2004 due
         primarily to the benefit in 2004 of selling cobalt finished goods
         inventory that was manufactured using raw materials that were purchased
         before the rapid increase in the cobalt price near the end of 2003. In
         2005, the opposite occurred - as cobalt prices declined - negatively
         impacting 2005 profitability.

         Since the Company has not yet finalized its second quarter 2005 results
         and publicly released its earnings, it is not possible at this time to
         discuss further any changes in the results of operations between the
         second quarters of 2005 and 2004.



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                                 OM Group, Inc.
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                  (Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned
hereunto duly authorized.


Date August 9, 2005                    By /s/ R. Louis Schneeberger
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