<PAGE>

      As filed with the Securities and Exchange Commission on May 25, 2000
                                            Registration Statement No. 333-
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549

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

                            REGISTRATION STATEMENT
                                  ON FORM S-8
                       UNDER THE SECURITIES ACT OF 1933

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

                             PURE RESOURCES, INC.
            (Exact name of registrant as specified in its charter)


           Delaware                                        74-2952918
  (State or other jurisdiction                          (I.R.S. Employer
of incorporation or organization)                      Identification No.)


      500 West Texas, Suite 200                               79701
         Midland, Texas  79701                             (Zip Code)
 (Address of principal executive offices)

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

            Pure Resources, Inc. Equity Plan for Outside Directors
                             (Full title of plan)

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

                               Jack D. Hightower
                           500 West Texas, Suite 200
                             Midland, Texas 79701
                                (915) 498-8600
           (Name, address and telephone number of agent for service)

                                   Copy to:
                                Joe Dannenmaier
                           Thompson & Knight L.L.P.
                        1700 Pacific Avenue, Suite 3300
                              Dallas, Texas 75201
                                (214) 969-1700

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


                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>

==================================================================================================================================
       Title of securities to be           Amount to be    Proposed maximum offering        Proposed maximum         Amount of
               registered                 registered (1)       price per share(2)          aggregate offering     registration fee
                                                                                               price (2)
----------------------------------------------------------------------------------------------------------------------------------
<S>                                       <C>              <C>                             <C>                    <C>
Common Stock, par value $.01 per share       200,000
                                             shares                 $13.36                     $2,672,980              $706
==================================================================================================================================

</TABLE>

(1)  Pursuant to Rule 416 under the Securities Act of 1933, this Registration
     Statement shall also be deemed to register  such additional indeterminate
     shares as may be issuable as a result of a stock split, stock dividend or
     similar transaction with respect to the shares covered hereby.

(2)  Estimated solely for the purpose of determining the registration fee
     pursuant to Rule 457, with price per share based on the market value of the
     Titan Exploration, Inc. Common Stock to be exchanged in the merger
     described in "Introductory Statement"), as the quotient of (a) $5.75 (the
     average of the high and low sales prices for Titan Exploration, Inc. Common
     Stock on the Nasdaq National Market on May 19, 2000) by  (b) the exchange
     ratio for the merger of .4302314 shares of Pure Resources, Inc. Common
     Stock for each outstanding share of Titan Exploration, Inc. Common Stock.

================================================================================
<PAGE>

                            INTRODUCTORY STATEMENT


     Pursuant to an Agreement and Plan of Merger (the "Merger Agreement") dated
as of December 13, 1999, as amended, Titan Exploration, Inc. ("Titan") and the
Registrant intend to consummate on May 25, 2000 a merger (the "Merger") whereby
a wholly-owned subsidiary of the Registrant will be merged with and into Titan,
with Titan surviving the Merger as a wholly-owned subsidiary of the Registrant.
In the Merger, shares of Titan common stock will be converted into the right to
receive shares of the Registrant's common stock. This Registration Statement
relates to 200,000 shares of the Registrant's common stock which may be issued
after the Merger under the Pure Resources, Inc. Equity Plan for Outside
Directors.


                                    PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.*
         ----------------

Item 2.  Registrant Information and Employee Plan Annual Information.*
         -----------------------------------------------------------

_____________

*  Information required by Part I to be contained in the Section 10(a)
   prospectus is omitted from this Registration Statement in accordance with
   Rule 428 under the Securities Act of 1933 and the Note to Part I of Form S-8.
<PAGE>

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.
          ---------------------------------------

     The following documents have been filed by the Registrant with the
Securities and Exchange Commission and are incorporated by reference in this
Registration Statement:

     (1)  The proxy statement/prospectus included in the Registrant's
          Registration Statement on Form S-4 (No. 333-34970) filed on April 18,
          2000.

     (2)  The description of the Registrant's Common Stock, $.01 par value per
          share, contained in the Registration Statement on Form 8-A of the
          Company heretofore filed with the Commission, including any amendments
          or reports filed for the purpose of updating such description.

     In addition, all documents filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934 subsequent to
the date of this Registration Statement and prior to the filing of a post-
effective amendment which indicates that all securities offered have been sold
or which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference in this Registration Statement and to be a part hereof
from the date of filing of such documents.  Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any other subsequently
filed document which also is or is deemed to be incorporated by reference herein
modifies or supersedes such statement.  Any statement so modified or superseded
shall not be deemed, except as so modified or superseded, to constitute a part
of this Registration Statement.  Upon the written or oral request of any person
to whom a copy of this Registration Statement has been delivered, the Company
will provide without charge to such person a copy of any and all documents
(excluding exhibits thereto unless such exhibits are specifically incorporated
by reference into such documents) that have been incorporated by reference into
this Registration Statement but not delivered herewith.  Requests for such
documents should be addressed to Pure Resources, Inc., 500 West Texas, Suite
200, Midland, Texas  79701, Attention:  Corporate Secretary, (915) 498-8600.


Item 4.   Description of Securities.
          -------------------------

     Not applicable.


Item 5.   Interests of Named Experts and Counsel.
          --------------------------------------

     Not Applicable.


Item 6.   Indemnification of Directors and Officers.
          -----------------------------------------

     Section 102(b) of the Delaware General Corporation Law ("DGCL") allows a
corporation to include in its certificate of incorporation a provision to
eliminate or limit the personal liability of a director to the registrant or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except in cases where the director breached his or her duty of loyalty to the
registrant or its stockholders, failed to act in good faith, engaged in
intentional misconduct or a knowing violation of a law, willfully or negligently
authorized the unlawful payment of a dividend or approved an illegal stock
repurchase (as provided in Section 174 of the DGCL) or obtained an improper
personal benefit.  The registrant's certificate of incorporation, as amended,
contains provisions that eliminate directors' personal liability, in certain
circumstances, as set forth below.

                                      II-1
<PAGE>

     The registrant's certificate of incorporation, as amended, provides, that a
director will not be personally liable to the registrant or its stockholders for
monetary damages for breach of duty as a director, except for liability (i) for
any breach of the director's duty of loyalty to the registrant or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
the DGCL or (iv) for any transaction from which the director derived an improper
personal benefit.

     The registrant's certificate of incorporation, as amended, provides that
each person who was or is made a party or is threatened to be made a party to or
is involved in any action, suit or proceeding, whether civil, criminal,
administrative or investigative (hereinafter a "proceeding"), by reason of the
fact that he or she, or a person of whom he or she is the legal representative,
is or was a director or officer of the registrant, or serves, in any capacity,
any corporation, partnership or other entity in which the registrant has a
partnership or other interest, including service with respect to employee
benefit plans, whether the basis of such proceeding is alleged action in an
official capacity as a director, officer, employee or agent or in any other
capacity while serving as a director, officer, employee or agent, shall be
indemnified and held harmless by the registrant to the fullest extent authorized
by the DGCL, as the same exists or may hereafter be amended (but, in case of any
such amendment, only to the extent that such amendment permits the registrant to
provide broader indemnification rights than said law permitted the registrant to
provide prior to such amendment), against all expense, liability and loss
(including attorneys' fees, judgments, fines, ERISA excise taxes or penalties
and amounts paid or to be paid in settlement) reasonably incurred or suffered by
such person in connection therewith and such indemnification shall continue as
to a person who has ceased to be a director, officer, employee or agent and
shall inure to the benefit of his or her heirs, executors and administrators.

     Pursuant to the registrant's certificate of incorporation, as amended, it
shall indemnify and hold harmless in such manner any person designated by the
Board of Directors, or any authorized committee thereof, as a person subject to
this indemnification provision, and who was or is made a party or is threatened
to be made a party to a proceeding by reason of the fact that he, she or a
person of whom he or she is the legal representative, is or was serving at the
request of the Board of Directors of the registrant as a director, officer,
employee or agent of another corporation or a partnership, joint venture, trust
or other enterprise whether such request is made before or after the acts taken
or allegedly taken or events occurring or allegedly occurring which give rise to
such proceeding.

     The registrant has a duty to indemnify any person seeking indemnification
pursuant to the registrant's certificate of incorporation in connection with a
proceeding (or part thereof) initiated by that person only if the proceeding (or
part thereof) was authorized by the Board of Directors of the registrant.

     The registrant may, by action of its Board of Directors, provide
indemnification to employees or agents of the registrant with the same scope and
effect as the foregoing indemnification of directors and officers.

     The registrant may maintain insurance, at its expense, to protect itself
and any director officer, employee or agent of the registrant or another
corporation, partnership, joint venture, trust or other enterprise against any
such expense, liability or loss, whether or not the registrant would have the
power to indemnify such person against such expense, liability or loss under the
DGCL.

Item 7.   Exemption from Registration Claimed.
          -----------------------------------

     Not Applicable.


Item 8.   Exhibits.
          --------

     The following documents are filed as exhibits to this Registration
Statement:

          4.1    Pure Resources, Inc. Equity Plan for Outside Directors (filed
                 as Exhibit 10.9 to the Registrant's Form S-4 (No. 333-34970)
                 and incorporated herein by reference).

                                      II-2
<PAGE>

          4.2    Agreement and Plan of Merger, dated as of December 13, 1999, by
                 and among Union Oil Company of California, Pure Resources, Inc.
                 (formerly named Titan Resources Holdings, Inc.), TRH, Inc. and
                 Titan Exploration, Inc. and Amendment No. 1 to Merger Agreement
                 dated as of April 14, 2000 (filed as Exhibit 2.1 to Titan
                 Exploration, Inc.'s Current Report on Form 8-K filed on
                 December 23, 1999 and Exhibit 2.2 to the Registrant's Form S-4
                 (No. 333-34970) and incorporated herein by reference).

          5.1    Opinion of Thompson & Knight L.L.P.

          23.1   Consent of Thompson & Knight L.L.P. (included in the opinion of
                 Thompson & Knight L.L.P. filed herewith as Exhibit 5.1).

          23.2   Consent of KPMG LLP.

          23.3   Consent of PricewaterhouseCoopers LLP

          23.4   Consent of Williamson Petroleum Consultants, Inc., independent
                 petroleum engineers.

          23.5   Consent of Gary Dupriest, Vice President of Pure Resources.

          23.6   Consent of Twachtman Snyder & Byrd, Inc., independent
                 consultants.

          24.1   Power of Attorney (included on signature page of this
                 Registration Statement).


Item 9.   Undertakings.
          ------------

     The Registrant hereby undertakes:

          (1)    To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement:

                 (i)    To include any prospectus required by Section 10(a)(3)
          of the Securities Act of 1933;

                 (ii)   To reflect in the prospectus any facts or events arising
          after the effective date of this Registration Statement (or the most
          recent post-effective amendment thereof) which, individually or in the
          aggregate, represent a fundamental change in the information set forth
          in this Registration Statement. Notwithstanding the foregoing, any
          increase or decrease in volume of securities offered (if the total
          dollar value of securities offered would not exceed that which was
          registered) and any deviation from the low or high end of the
          estimated maximum offering range may be reflected in the Form of
          prospectus filed with the Commission pursuant to Rule 424(b) if, in
          the aggregate, the changes in volume and price represent no more than
          a 20% change in the maximum aggregate offering price set forth in the
          "Calculation of Registration Fee" table in the effective registration
          statement; and

                 (iii)  To include any material information with respect to the
          plan of distribution not previously disclosed in this Registration
          Statement or any material change to such information in this
          Registration Statement;

   provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if the
   information required to be included in a post-effective amendment by those
   paragraphs is contained in periodic reports filed by the Registrant pursuant
   to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that
   are incorporated by reference in this Registration Statement.

                                      II-3
<PAGE>

          (2)    That, for the purpose of determining any liability under the
     Securities Act of 1933, each such post-effective amendment shall be deemed
     to be a new registration statement relating to the securities offered
     therein, and the offering of such securities at that time shall be deemed
     to be the initial bona fide offering thereof.

          (3)    To remove from registration by means of a post-effective
     amendment any of the securities being registered which remain unsold at the
     termination of the offering.

          (4)    That, for purposes of determining any liability under the
     Securities Act of 1933, each filing of the Registrant's annual report
     pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act
     of 1934 that is incorporated by reference in this Registration Statement
     shall be deemed to be a new registration statement relating to the
     securities offered therein, and the offering of such securities at that
     time shall be deemed to be the initial bona fide offering thereof.

          (5)    Insofar as indemnification for liabilities arising under the
     Securities Act of 1933 may be permitted to directors, officers and
     controlling persons of the Registrant pursuant to the foregoing provisions,
     or otherwise, the Registrant has been advised that in the opinion of the
     Securities and Exchange Commission such indemnification is against public
     policy as expressed in the Act and is, therefore, unenforceable. In the
     event that a claim for indemnification against such liabilities (other than
     the payment by the Registrant of expenses incurred or paid by a director,
     officer or controlling person of the Registrant in the successful defense
     of any action, suit or proceeding) is asserted by such director, officer or
     controlling person in connection with the securities being registered, the
     Registrant will, unless in the opinion of its counsel the matter has been
     settled by controlling precedent, submit to a court of appropriate
     jurisdiction the question whether such indemnification by it is against
     public policy as expressed in the Act and will be governed by the final
     adjudication of such issue.

                                      II-4
<PAGE>

                                  SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
has duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Sugarland, State of
Texas, on the 24th day of May, 2000.

                                     PURE RESOURCES, INC.


                                     By:  /s/ Timothy H. Ling
                                        ------------------------------
                                          Timothy H. Ling
                                          President



     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.  Each person whose signature appears
below constitutes and appoints Barry Hoffman and Phillip Ballard, and each of
them (with full power to each of them to act alone), his true and lawful
attorney-in-fact and agent, with full power of substitution and resubstitution,
for him and in his name, place and stead, in any and all capacities to sign on
his behalf individually and in each capacity stated below any amendment,
including post-effective amendments, to this Registration Statement, and to file
the same, with all exhibits thereto and other documents in connection therewith
with the Securities and Exchange Commission, granting unto said attorneys-in-
fact and agents, and each of them, full power and authority to do and perform
each and every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as he might or could do in
person, hereby ratifying and confirming all that said attorneys-in-fact and
agents and either of them, or their substitutes, may lawfully do or cause to be
done by virtue hereof.

        Signature                    Title                        Date
        ---------                    -----                        ----


/s/ Timothy H. Ling        President and Director              May 24, 2000
-------------------------  (Principal Executive Officer)
Timothy H. Ling



/s/ Darrell Chessum        Vice President, Treasurer           May 24, 2000
-------------------------  and Director
Darrell Chessum            (Principal Financial and
                           Accounting Officer)

                                      II-5
<PAGE>

                               INDEX TO EXHIBITS

Exhibit Number                      Exhibit
--------------                      -------

   4.1          Pure Resources, Inc. Equity Plan for Outside Directors (filed as
                Exhibit 10.9 to the Registrant's Form S-4 (No. 333-34970) and
                incorporated herein by reference).

   4.2          Agreement and Plan of Merger, dated as of December 13, 1999, by
                and among Union Oil Company of California, Pure Resources, Inc.
                (formerly named Titan Resources Holdings, Inc.), TRH, Inc. and
                Titan Exploration, Inc. and Amendment No. 1 to Merger Agreement
                dated as of April 14, 2000 (filed as Exhibit 2.1 to Titan
                Exploration, Inc.'s Current Report on Form 8-K filed on December
                23, 1999 and Exhibit 2.2 to the Registrant's Form S-4 (No. 333-
                34970) and incorporated herein by reference).

   5.1          Opinion of Thompson & Knight L.L.P.

   23.1         Consent of Thompson & Knight L.L.P. (included in the opinion of
                Thompson & Knight L.L.P. filed herewith as Exhibit 5.1).

   23.2         Consent of KPMG LLP.

   23.3         Consent of PricewaterhouseCoopers LLP

   23.4         Consent of Williamson Petroleum Consultants, Inc., independent
                petroleum engineers.

   23.5         Consent of Gary Dupriest, Vice President of Pure Resources.

   23.6         Consent of Twachtman Snyder & Byrd, Inc., independent
                consultants.

   24.1         Power of Attorney (included on signature page of this
                Registration Statement).

                                      II-6
[{"type": "S-8", "sequence": "1", "description": "FORM S-8 -- EQUITY PLAN FOR OUTSIDE DIRECTORS", "secsgml_size_bytes": 23608}]
{"company-data": {"conformed-name": "PURE RESOURCES INC", "cik": "0001109860", "assigned-sic": "1382", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-37870", "film-number": "643910"}, "business-address": {"street1": "2141 ROSECRANS AVENUE", "street2": "SUITE 4000", "city": "EL SEGUNDON", "state": "CA", "zip": "90245", "phone": "3107267768"}, "mail-address": {"street1": "2141 ROSECRANS AVENUE", "street2": "SUITE 4000", "city": "ELSEGUNDO", "state": "CA", "zip": "90245"}}
As filed with the Securities and Exchange Commission on May 25, 2000
                                            Registration Statement No. 333-
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549

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

                            REGISTRATION STATEMENT
                                  ON FORM S-8
                       UNDER THE SECURITIES ACT OF 1933

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

                             PURE RESOURCES, INC.
            (Exact name of registrant as specified in its charter)

           Delaware                                        74-2952918
  (State or other jurisdiction                          (I.R.S. Employer
of incorporation or organization)                      Identification No.)

      500 West Texas, Suite 200                               79701
         Midland, Texas  79701                             (Zip Code)
 (Address of principal executive offices)

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

            Pure Resources, Inc. Equity Plan for Outside Directors
                             (Full title of plan)

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

                               Jack D. Hightower
                           500 West Texas, Suite 200
                             Midland, Texas 79701
                                (915) 498-8600
           (Name, address and telephone number of agent for service)

                                   Copy to:
                                Joe Dannenmaier
                           Thompson & Knight L.L.P.
                        1700 Pacific Avenue, Suite 3300
                              Dallas, Texas 75201
                                (214) 969-1700

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

                        CALCULATION OF REGISTRATION FEE
==================================================================================================================================
       Title of securities to be           Amount to be    Proposed maximum offering        Proposed maximum         Amount of
               registered                 registered (1)       price per share(2)          aggregate offering     registration fee
                                                                                               price (2)
----------------------------------------------------------------------------------------------------------------------------------
Common Stock, par value $.01 per share       200,000
                                             shares                 $13.36                     $2,672,980              $706
==================================================================================================================================
(1)  Pursuant to Rule 416 under the Securities Act of 1933, this Registration
     Statement shall also be deemed to register  such additional indeterminate
     shares as may be issuable as a result of a stock split, stock dividend or
     similar transaction with respect to the shares covered hereby.

(2)  Estimated solely for the purpose of determining the registration fee
     pursuant to Rule 457, with price per share based on the market value of the
     Titan Exploration, Inc. Common Stock to be exchanged in the merger
     described in "Introductory Statement"), as the quotient of (a) $5.75 (the
     average of the high and low sales prices for Titan Exploration, Inc. Common
     Stock on the Nasdaq National Market on May 19, 2000) by  (b) the exchange
     ratio for the merger of .4302314 shares of Pure Resources, Inc. Common
     Stock for each outstanding share of Titan Exploration, Inc. Common Stock.

================================================================================
INTRODUCTORY STATEMENT

     Pursuant to an Agreement and Plan of Merger (the "Merger Agreement") dated
as of December 13, 1999, as amended, Titan Exploration, Inc. ("Titan") and the
Registrant intend to consummate on May 25, 2000 a merger (the "Merger") whereby
a wholly-owned subsidiary of the Registrant will be merged with and into Titan,
with Titan surviving the Merger as a wholly-owned subsidiary of the Registrant.
In the Merger, shares of Titan common stock will be converted into the right to
receive shares of the Registrant's common stock. This Registration Statement
relates to 200,000 shares of the Registrant's common stock which may be issued
after the Merger under the Pure Resources, Inc. Equity Plan for Outside
Directors.

                                    PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.*
         ----------------

Item 2.  Registrant Information and Employee Plan Annual Information.*
         -----------------------------------------------------------

_____________

*  Information required by Part I to be contained in the Section 10(a)
   prospectus is omitted from this Registration Statement in accordance with
   Rule 428 under the Securities Act of 1933 and the Note to Part I of Form S-8.
PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.
          ---------------------------------------

     The following documents have been filed by the Registrant with the
Securities and Exchange Commission and are incorporated by reference in this
Registration Statement:

     (1)  The proxy statement/prospectus included in the Registrant's
          Registration Statement on Form S-4 (No. 333-34970) filed on April 18,
          2000.

     (2)  The description of the Registrant's Common Stock, $.01 par value per
          share, contained in the Registration Statement on Form 8-A of the
          Company heretofore filed with the Commission, including any amendments
          or reports filed for the purpose of updating such description.

     In addition, all documents filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934 subsequent to
the date of this Registration Statement and prior to the filing of a post-
effective amendment which indicates that all securities offered have been sold
or which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference in this Registration Statement and to be a part hereof
from the date of filing of such documents.  Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any other subsequently
filed document which also is or is deemed to be incorporated by reference herein
modifies or supersedes such statement.  Any statement so modified or superseded
shall not be deemed, except as so modified or superseded, to constitute a part
of this Registration Statement.  Upon the written or oral request of any person
to whom a copy of this Registration Statement has been delivered, the Company
will provide without charge to such person a copy of any and all documents
(excluding exhibits thereto unless such exhibits are specifically incorporated
by reference into such documents) that have been incorporated by reference into
this Registration Statement but not delivered herewith.  Requests for such
documents should be addressed to Pure Resources, Inc., 500 West Texas, Suite
200, Midland, Texas  79701, Attention:  Corporate Secretary, (915) 498-8600.

Item 4.   Description of Securities.
          -------------------------

     Not applicable.

Item 5.   Interests of Named Experts and Counsel.
          --------------------------------------

     Not Applicable.

Item 6.   Indemnification of Directors and Officers.
          -----------------------------------------

     Section 102(b) of the Delaware General Corporation Law ("DGCL") allows a
corporation to include in its certificate of incorporation a provision to
eliminate or limit the personal liability of a director to the registrant or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except in cases where the director breached his or her duty of loyalty to the
registrant or its stockholders, failed to act in good faith, engaged in
intentional misconduct or a knowing violation of a law, willfully or negligently
authorized the unlawful payment of a dividend or approved an illegal stock
repurchase (as provided in Section 174 of the DGCL) or obtained an improper
personal benefit.  The registrant's certificate of incorporation, as amended,
contains provisions that eliminate directors' personal liability, in certain
circumstances, as set forth below.

                                      II-1
The registrant's certificate of incorporation, as amended, provides, that a
director will not be personally liable to the registrant or its stockholders for
monetary damages for breach of duty as a director, except for liability (i) for
any breach of the director's duty of loyalty to the registrant or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
the DGCL or (iv) for any transaction from which the director derived an improper
personal benefit.

     The registrant's certificate of incorporation, as amended, provides that
each person who was or is made a party or is threatened to be made a party to or
is involved in any action, suit or proceeding, whether civil, criminal,
administrative or investigative (hereinafter a "proceeding"), by reason of the
fact that he or she, or a person of whom he or she is the legal representative,
is or was a director or officer of the registrant, or serves, in any capacity,
any corporation, partnership or other entity in which the registrant has a
partnership or other interest, including service with respect to employee
benefit plans, whether the basis of such proceeding is alleged action in an
official capacity as a director, officer, employee or agent or in any other
capacity while serving as a director, officer, employee or agent, shall be
indemnified and held harmless by the registrant to the fullest extent authorized
by the DGCL, as the same exists or may hereafter be amended (but, in case of any
such amendment, only to the extent that such amendment permits the registrant to
provide broader indemnification rights than said law permitted the registrant to
provide prior to such amendment), against all expense, liability and loss
(including attorneys' fees, judgments, fines, ERISA excise taxes or penalties
and amounts paid or to be paid in settlement) reasonably incurred or suffered by
such person in connection therewith and such indemnification shall continue as
to a person who has ceased to be a director, officer, employee or agent and
shall inure to the benefit of his or her heirs, executors and administrators.

     Pursuant to the registrant's certificate of incorporation, as amended, it
shall indemnify and hold harmless in such manner any person designated by the
Board of Directors, or any authorized committee thereof, as a person subject to
this indemnification provision, and who was or is made a party or is threatened
to be made a party to a proceeding by reason of the fact that he, she or a
person of whom he or she is the legal representative, is or was serving at the
request of the Board of Directors of the registrant as a director, officer,
employee or agent of another corporation or a partnership, joint venture, trust
or other enterprise whether such request is made before or after the acts taken
or allegedly taken or events occurring or allegedly occurring which give rise to
such proceeding.

     The registrant has a duty to indemnify any person seeking indemnification
pursuant to the registrant's certificate of incorporation in connection with a
proceeding (or part thereof) initiated by that person only if the proceeding (or
part thereof) was authorized by the Board of Directors of the registrant.

     The registrant may, by action of its Board of Directors, provide
indemnification to employees or agents of the registrant with the same scope and
effect as the foregoing indemnification of directors and officers.

     The registrant may maintain insurance, at its expense, to protect itself
and any director officer, employee or agent of the registrant or another
corporation, partnership, joint venture, trust or other enterprise against any
such expense, liability or loss, whether or not the registrant would have the
power to indemnify such person against such expense, liability or loss under the
DGCL.

Item 7.   Exemption from Registration Claimed.
          -----------------------------------

     Not Applicable.

Item 8.   Exhibits.
          --------

     The following documents are filed as exhibits to this Registration
Statement:

          4.1    Pure Resources, Inc. Equity Plan for Outside Directors (filed
                 as Exhibit 10.9 to the Registrant's Form S-4 (No. 333-34970)
                 and incorporated herein by reference).

                                      II-2
4.2    Agreement and Plan of Merger, dated as of December 13, 1999, by
                 and among Union Oil Company of California, Pure Resources, Inc.
                 (formerly named Titan Resources Holdings, Inc.), TRH, Inc. and
                 Titan Exploration, Inc. and Amendment No. 1 to Merger Agreement
                 dated as of April 14, 2000 (filed as Exhibit 2.1 to Titan
                 Exploration, Inc.'s Current Report on Form 8-K filed on
                 December 23, 1999 and Exhibit 2.2 to the Registrant's Form S-4
                 (No. 333-34970) and incorporated herein by reference).

          5.1    Opinion of Thompson & Knight L.L.P.

          23.1   Consent of Thompson & Knight L.L.P. (included in the opinion of
                 Thompson & Knight L.L.P. filed herewith as Exhibit 5.1).

          23.2   Consent of KPMG LLP.

          23.3   Consent of PricewaterhouseCoopers LLP

          23.4   Consent of Williamson Petroleum Consultants, Inc., independent
                 petroleum engineers.

          23.5   Consent of Gary Dupriest, Vice President of Pure Resources.

          23.6   Consent of Twachtman Snyder & Byrd, Inc., independent
                 consultants.

          24.1   Power of Attorney (included on signature page of this
                 Registration Statement).

Item 9.   Undertakings.
          ------------

     The Registrant hereby undertakes:

          (1)    To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement:

                 (i)    To include any prospectus required by Section 10(a)(3)
          of the Securities Act of 1933;

                 (ii)   To reflect in the prospectus any facts or events arising
          after the effective date of this Registration Statement (or the most
          recent post-effective amendment thereof) which, individually or in the
          aggregate, represent a fundamental change in the information set forth
          in this Registration Statement. Notwithstanding the foregoing, any
          increase or decrease in volume of securities offered (if the total
          dollar value of securities offered would not exceed that which was
          registered) and any deviation from the low or high end of the
          estimated maximum offering range may be reflected in the Form of
          prospectus filed with the Commission pursuant to Rule 424(b) if, in
          the aggregate, the changes in volume and price represent no more than
          a 20% change in the maximum aggregate offering price set forth in the
          "Calculation of Registration Fee" table in the effective registration
          statement; and

                 (iii)  To include any material information with respect to the
          plan of distribution not previously disclosed in this Registration
          Statement or any material change to such information in this
          Registration Statement;

   provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if the
   information required to be included in a post-effective amendment by those
   paragraphs is contained in periodic reports filed by the Registrant pursuant
   to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that
   are incorporated by reference in this Registration Statement.

                                      II-3
(2)    That, for the purpose of determining any liability under the
     Securities Act of 1933, each such post-effective amendment shall be deemed
     to be a new registration statement relating to the securities offered
     therein, and the offering of such securities at that time shall be deemed
     to be the initial bona fide offering thereof.

          (3)    To remove from registration by means of a post-effective
     amendment any of the securities being registered which remain unsold at the
     termination of the offering.

          (4)    That, for purposes of determining any liability under the
     Securities Act of 1933, each filing of the Registrant's annual report
     pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act
     of 1934 that is incorporated by reference in this Registration Statement
     shall be deemed to be a new registration statement relating to the
     securities offered therein, and the offering of such securities at that
     time shall be deemed to be the initial bona fide offering thereof.

          (5)    Insofar as indemnification for liabilities arising under the
     Securities Act of 1933 may be permitted to directors, officers and
     controlling persons of the Registrant pursuant to the foregoing provisions,
     or otherwise, the Registrant has been advised that in the opinion of the
     Securities and Exchange Commission such indemnification is against public
     policy as expressed in the Act and is, therefore, unenforceable. In the
     event that a claim for indemnification against such liabilities (other than
     the payment by the Registrant of expenses incurred or paid by a director,
     officer or controlling person of the Registrant in the successful defense
     of any action, suit or proceeding) is asserted by such director, officer or
     controlling person in connection with the securities being registered, the
     Registrant will, unless in the opinion of its counsel the matter has been
     settled by controlling precedent, submit to a court of appropriate
     jurisdiction the question whether such indemnification by it is against
     public policy as expressed in the Act and will be governed by the final
     adjudication of such issue.

                                      II-4
SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
has duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Sugarland, State of
Texas, on the 24th day of May, 2000.

                                     PURE RESOURCES, INC.

                                     By:  /s/ Timothy H. Ling
                                        ------------------------------
                                          Timothy H. Ling
                                          President

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.  Each person whose signature appears
below constitutes and appoints Barry Hoffman and Phillip Ballard, and each of
them (with full power to each of them to act alone), his true and lawful
attorney-in-fact and agent, with full power of substitution and resubstitution,
for him and in his name, place and stead, in any and all capacities to sign on
his behalf individually and in each capacity stated below any amendment,
including post-effective amendments, to this Registration Statement, and to file
the same, with all exhibits thereto and other documents in connection therewith
with the Securities and Exchange Commission, granting unto said attorneys-in-
fact and agents, and each of them, full power and authority to do and perform
each and every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as he might or could do in
person, hereby ratifying and confirming all that said attorneys-in-fact and
agents and either of them, or their substitutes, may lawfully do or cause to be
done by virtue hereof.

        Signature                    Title                        Date
        ---------                    -----                        ----

/s/ Timothy H. Ling        President and Director              May 24, 2000
-------------------------  (Principal Executive Officer)
Timothy H. Ling

/s/ Darrell Chessum        Vice President, Treasurer           May 24, 2000
-------------------------  and Director
Darrell Chessum            (Principal Financial and
                           Accounting Officer)

                                      II-5
INDEX TO EXHIBITS

Exhibit Number                      Exhibit
--------------                      -------

   4.1          Pure Resources, Inc. Equity Plan for Outside Directors (filed as
                Exhibit 10.9 to the Registrant's Form S-4 (No. 333-34970) and
                incorporated herein by reference).

   4.2          Agreement and Plan of Merger, dated as of December 13, 1999, by
                and among Union Oil Company of California, Pure Resources, Inc.
                (formerly named Titan Resources Holdings, Inc.), TRH, Inc. and
                Titan Exploration, Inc. and Amendment No. 1 to Merger Agreement
                dated as of April 14, 2000 (filed as Exhibit 2.1 to Titan
                Exploration, Inc.'s Current Report on Form 8-K filed on December
                23, 1999 and Exhibit 2.2 to the Registrant's Form S-4 (No. 333-
                34970) and incorporated herein by reference).

   5.1          Opinion of Thompson & Knight L.L.P.

   23.1         Consent of Thompson & Knight L.L.P. (included in the opinion of
                Thompson & Knight L.L.P. filed herewith as Exhibit 5.1).

   23.2         Consent of KPMG LLP.

   23.3         Consent of PricewaterhouseCoopers LLP

   23.4         Consent of Williamson Petroleum Consultants, Inc., independent
                petroleum engineers.

   23.5         Consent of Gary Dupriest, Vice President of Pure Resources.

   23.6         Consent of Twachtman Snyder & Byrd, Inc., independent
                consultants.

   24.1         Power of Attorney (included on signature page of this
                Registration Statement).

                                      II-6