--------                                        -----------------------------
 FORM 4                                                  OMB APPROVAL
--------                                        -----------------------------
----- Check this box if no longer               OMB Number:       3235-0287
      subject to Section 16. Form 4             Expires: January 31, 2005
----- or Form 5 obligations may                 Estimated average burden
      continue. SEE Instruction 1(b).           hours per response .... 0.5
                                                -----------------------------

              UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                       WASHINGTON, D.C. 20549

                 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

     Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934,
      Section 17(a) of the Public Utility Holding Company Act of 1935 or
             Section 30(f) of the Investment Company Act of 1940

(Print or Type Responses)

- ---------------------------------------------------------------------------
1. Name and Address of Reporting Person*

   Ardsley Advisory Partners
- ---------------------------------------------------
   (Last)           (First)            (Middle)

   262 Harbor Drive
- ----------------------------------------------------
                    (Street)

   Stamford           CT                  06902
- ----------------------------------------------------
   (City)           (State)               (Zip)

- ---------------------------------------------------------------------------
2. Issuer Name and Ticker or Trading Symbol

    OM Group, Inc. (OMG)
- ---------------------------------------------------------------------------
3. IRS or Social Security Number of Reporting Person (Voluntary)

- ---------------------------------------------------------------------------

4. Statement for Month/Day/Year

   02/04/03-02/05/2003
- ---------------------------------------------------------------------------
5. If Amendment, Date of Original (Month/Day/Year)

- ---------------------------------------------------------------------------


                                                                     Page 1 of 7




6. Relationship of Reporting Person(s) to Issuer (Check all applicable)

   [ ] Director
   [X] 10% Owner
   [ ] Officer (give title below)
   [ ] Other (specify below)

- ---------------------------------------------------------------------------
7. Individual or Joint/Group Filing (Check Applicable Line)

   [ ] Form filed by One Reporting Person
   [X] Form filed by More than One Reporting Person
- ---------------------------------------------------------------------------


TABLE I--NON-DERIVATIVE SECURITIES ACQUIRED, DISPOSED OF, OR BENEFICIALLY
OWNED
----------------------------------------------------------------------------
1. Title of    2. Trans-    2A. Deemed    3. Trans-    4. Securities Acquired
   Security       action        Execution    action       (A) or Disposed of (D)
   (Instr. 3)     Date          Date, if     Code         (Instr. 3, 4 and 5)
                  (Month/       any (Month/  (Instr. 8)  ----------------------
                  Day/          Day/         ----------  Amount  (A) or  Price
                  Year)         Year)         Code   V           (D)


----------------------------------------------------------------------------
----------------------------------------------------------------------------
OM Group Inc., Common Stock,
$0.01 par value
per share
("Common Stock")  02/04/03                  P         50,000     A    $8.6556
----------------------------------------------------------------------------
Common Stock      02/05/03                  P         50,000 V    A    $8.42
----------------------------------------------------------------------------

                                                                     Page 2 of 7




5. Amount of        6. Ownership        7. Nature of
   Securities          Form: Direct        Indirect
   Beneficially        (D) or Indirect     Beneficial
   Owned following     (I) (Instr. 4)      Ownership
   Reported                                (Instr. 4)
   Transactions
   (Instr. 3
      and 4)
----------------------------------------------------------------------------
   4,054,200            I(1)(2)                (1)(2)
----------------------------------------------------------------------------



Reminder: Report on a separate line for each class of securities
beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, SEE
Instruction 4(b)(v).


TABLE II - DERIVATIVE SECURITIES ACQUIRED, DISPOSED OF, OR BENEFICIALLY OWNED
           (E.G., PUTS, CALLS, WARRANTS, OPTIONS, CONVERTIBLE SECURITIES)
----------------------------------------------------------------------------
1. Title of Derivative  2. Conver-  3. Transac-  4. Transac-  5. Number of
   Security (Instr. 3)     sion or     tion Date    tion Code    Derivative
                           Exercise    (Month/      (Instr. 8)   Securities
                           Price of     Day/      ------------   Acquired (A)
                           Deriv-       Year)      Code   V      or Disposed
                           ative                                 of (D) (Instr.
                           Security                              3, 4, and 5)
                                                                 -------------
                                                                  (A)     (D)
----------------------------------------------------------------------------
----------------------------------------------------------------------------
6. Date Exer-      7. Title and Amount       8. Price of
   cisable and        of Underlying             Derivative
   Expiration Date    Securities                Security
   (Month/Day/        (Instr. 3 and 4)          (Instr. 5)
   Year)             -------------------
-----------------            Amount or
Date     Expira-      Title  Number of
Exer-    tion                Shares
cisable  Date
----------------------------------------------------------------------------
----------------------------------------------------------------------------

                                                                     Page 3 of 7




----------------------------------------------------------------------------
9. Number of        10. Ownership        11. Nature of
   Derivative           Form of              Indirect
   Securities           Derivative           Beneficial
   Beneficially         Security:            Ownership
   Owned at             Direct (D) or        (Instr. 4)
   End of Month         Indirect (I)
   (Instr. 4)           (Instr. 4)
----------------------------------------------------------------------------
----------------------------------------------------------------------------

----------------------------------------------------------------------------


Explanation of Responses

(1)  The shares of Common Stock to which this note relates are held  directly by
     Ardsley Offshore Fund Ltd., a British Virgin Islands corporation  ("Ardsley
     Offshore"),  as to  1,175,000  shares;  Ardsley  Partners  Fund II, L.P., a
     Delaware limited  partnership  ("Ardsley Fund II"), as to 1,025,000 shares;
     Ardsley Partners  Institutional Fund, L.P., a Delaware limited partnership,
     ("Ardsley  Institutional"),  as to 535,000 shares;  Augusta Partners L.P. a
     Delaware limited partnership  ("Augusta"),  as to 515,000 shares; Philip J.
     Hempleman,  the  managing  partner of  Ardsley  Advisory  Partners  and the
     general  partner of Ardsley  Partners  I as to 470,000  shares;  the Carter
     Hempleman  Trust  ("Carter  Trust"),  as  to  92,000  shares;  the  Spencer
     Hempleman  Trust  ("Spencer  Trust"),  as to 92,200  shares;  the Hempleman
     Family Trust  ("Family  Trust"),  as to 100,000  shares;  and Marion Lynton
     ("Lynton") as to 50,000 shares.

(2)  Ardsley  Advisory  Partners  serves  as  investment  manager  to,  and  has
     investment  discretion over the securities held by Ardsley Offshore and the
     Lynton  account.  Ardsley  Advisory  Partners also serves as a non-managing
     member of Augusta  Management L.L.C., the investment advisor to Augusta and
     has  investment  discretion  over the securities  held by Augusta.  Ardsley
     Partners I serves as the general partner of, and has investment  discretion
     over the  securities  held by Ardsley  Fund II and  Ardsley  Institutional.
     Ardsley  Partners I also serves as the general partner of Ardsley  Advisory
     Partners. Philip Hempleman serves as trustee to and has discretion over the
     securities  held by the  Carter  Trust,  the  Spencer  Trust and the Family
     Trust.  Ardsley Advisory  Partners and Ardsley Partners I each disclaim any
     beneficial ownership of any of the Issuer's securities to which this Form 4
     relates for the  purposes of Section 16 of the  Securities  Exchange Act of
     1934, as amended,  except as to such securities  representing in which each
     such person may be deemed to have an indirect  pecuniary  interest pursuant
     to Rule 16a-1(a)(2).


                                                                     Page 4 of 7




* If the form is filed by more than one reporting person, SEE
Instruction 4(b)(v).

**Intentional misstatements or omissions of facts constitute Federal Criminal
Violations.  SEE 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this form, one of which must be manually signed.
If space is insufficient, SEE Instruction 6 for procedure.

                                 ARDSLEY ADVISORY PARTNERS

                                   /s/ Philip J. Hempleman             02/06/03
                                 ---------------------------------     --------
                                    Name: Philip J. Hempleman            Date
                                    Title: Managing Partner

                             Joint Filer Information

Name:  Ardsley Partners Fund II, L.P.
Address:   262 Harbor Drive, Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature: Ardsley Partners Fund II, L.P.

                  By: Ardsley Partners I, its general partner
                  By:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: General Partner

Name: Ardsley Partners Institutional Fund, L.P.
Address:   262 Harbor Drive, Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature: Ardsley Partners Institutional Fund, L.P.

                  By: Ardsley Partners I, its general partner
                  By:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: General Partner

Name:  Ardsley Partners I
Address:   262 Harbor Drive, Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature: Ardsley Partners I

                  By:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: General Partner


                                                                     Page 5 of 7




Name: Philip J. Hempleman
Address:  c/o Ardsley Advisory Partners  262 Harbor Drive,
          Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature:             /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman

Name: Carter Hempleman Trust
Address:  c/o Ardsley Advisory Partners  262 Harbor Drive,
          Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature:        Carter Hempleman Trust

                  BY:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: Trustee

Name: Spencer Hempleman Trust
Address:  c/o Ardsley Advisory Partners  262 Harbor Drive,
          Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03
Signature:        Spencer Hempleman Trust

                  BY:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: Trustee

Name: Hempleman Family Trust
Address:  c/o Ardsley Advisory Partners  262 Harbor Drive,
          Stamford, Connecticut 06902
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature:        Hempleman Family Trust

                  BY:  /s/ Philip J. Hempleman
                  -----------------------------------------------------------
                     Name: Philip J. Hempleman
                     Title: Trustee



                                                                     Page 6 of 7




Name: Augusta Partners L.P.
Address:   622 Third Avenue, New York, New York 10017
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03

Signature:        Augusta Partners L.P.

                  By: /s/ Howard Singer
                  -----------------------------------------------------------
                     Name: Howard Singer
                     Title: General Partner

Name:  Ardsley Offshore Fund Ltd.
Address:  Romasaco Place, Wickhams Cay I, Roadtown Tortola,
          British Virgin Islands
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03
Signature:        Ardsley Offshore Fund, Ltd.

                  By: /s/ Neil Glass
                  -----------------------------------------------------------
                     Name: Neil Glass
                     Title: Vice President and Administrative Manager

Name: Marion Lynton
Address:  961 Senimore Road, Larchmont, NY 10538
Designated Filer:  Ardsley Advisory Partners
Issuer & Ticker Symbol:  OM Group, Inc.(OMG)
Date of Event Requiring Statement:   02/04/03-02/05/03
Signature:

                      /s/ Marion Lynton
                  -----------------------------------------------------------
                     Name: Marion Lynton












                                                                     Page 7 of 7