<PAGE>

                                                                             NO.

                         COMMON STOCK PURCHASE WARRANT

   THIS SECURITY AND ANY SHARES ISSUED UPON EXERCISE OF THIS SECURITY HAVE NOT
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR
APPLICABLE STATE SECURITIES LAWS AND MAY NOT BE TRANSFERRED OR OTHERWISE
DISPOSED OF UNLESS THE APPLICABLE SECURITY HAS BEEN REGISTERED UNDER THE ACT
AND SUCH LAWS OR (1) REGISTRATION UNDER SUCH LAWS IS NOT REQUIRED AND (2) AN
OPINION OF COUNSEL SATISFACTORY TO THE COMPANY IS FURNISHED TO THE COMPANY TO
THE EFFECT THAT REGISTRATION UNDER THE ACT AND THE APPLICABLE STATE SECURITIES
LAWS IS NOT REQUIRED.

                          ACACIA RESEARCH CORPORATION

WARRANT TO PURCHASE COMMON STOCK
   This certifies that, for value received,
("the Holder") is entitled to subscribe for and purchase up to
shares (subject to adjustment from time to time pursuant to the provisions of
Section 5 hereof) of fully paid and nonassessable Common Stock of Acacia
Research Corporation, a Delaware corporation (the "Company"), at the price
specified in Section 2 hereof, as such price may be adjusted from time to time
pursuant to Section 5 hereof (the "Warrant Price"), subject to the provisions
and upon the terms and conditions hereinafter set forth and callable by the
Company upon the terms and conditions set forth in Section 1 hereof.

   As used herein, the term "Common Stock" shall mean the Company's presently
authorized Common Stock, par value $0.001 per share, and any stock into or for
which such Common Stock may hereafter be converted or exchanged.

   This Warrant is issued pursuant to that certain Subscription Agreement
between the Holder and the Company dated            (the "Subscription
Agreement").

   l. Term of Warrant; Callability By Company.

   The purchase right represented by this Warrant is exercisable, in whole or
in part, at any time during a period beginning on the date hereof and ending
July 20, 2003. However, during the three-year period, the Company will have the
right to redeem all of the Warrants on 30 days prior written notice at a
redemption price of $0.10 per Warrant if (a) the closing bid price of the
Company's Common Stock averages $39.60 or above for 20 consecutive trading days
after the Common Stock reaches a closing bid price of at least $39.60 on the
Nasdaq National Market System and (b) the registration statement covering the
resale of the shares of the Company's Common Stock underlying this Warrant has
been declared effective by the Securities and Exchange Commission and remains
in effect. If the Company elects to exercise its redemption right, the Holder
of this Warrant may either exercise the Warrant, in whole or in part, or tender
the Warrant to the Company for redemption, in whole or in part. Within five
business days after the end of the 30-day period, the Company will mail a check
for the redemption price to the Holder of this Warrant should this Warrant
remain outstanding in whole or in part as of the end of the 30-day period,
whether or not the Holder has surrendered this Warrant for redemption. This
Warrant may not be exercised after the end of such 30-day period.
Notwithstanding the provisions of this Section 1, if for any reason, the
Company suspends or otherwise prohibits the Holder from distributing any shares
of the Company's Common Stock issuable pursuant to this Warrant pursuant to any
provision of Section 4 of the Subscription Agreement, the Company shall not
exercise its right to redeem this Warrant until such suspension or prohibition
is lifted.
<PAGE>

   2. Warrant Price

   The Warrant Price is $33.00 per share, subject to adjustment from time to
time pursuant to the provisions of Section 5 hereof.

   3. Method of Exercise: Payment; Issuance of New Warrant.

   Subject to Section 1 hereof, the purchase right represented by this Warrant
may be exercised by the Holder, in whole or in part, by the surrender of this
Warrant (with the notice of exercise form attached hereto as Exhibit 1 duly
executed) at the principal office of the Company and by the payment to the
Company, by cashier's check or wire transfer, of an amount equal to the then
applicable Warrant Price per share multiplied by the number of shares then
being purchased. The Company agrees that the shares so purchased shall be
deemed to be issued to the Holder as the record owner of such shares as of the
close of business on the date on which this Warrant shall have been surrendered
and payment made for such shares as aforesaid. In the event of any exercise of
the rights represented by this Warrant, certificates for the shares of stock so
purchased shall be delivered to the Holder within 15 days thereafter and,
unless this Warrant has been fully exercised or expired, a new Warrant
representing the portion of the shares, if any, with respect to which this
Warrant shall not then have been exercised, shall also be issued to the Holder
within such 15 day period.

   4. Stock Fully Paid; Reservation of Shares.

   All Common Stock which may be issued upon the exercise of the rights
represented by this Warrant will, upon issuance, be fully paid and
nonassessable, and free from all taxes, liens and charges with respect to the
issue thereof. During the period within which the rights represented by this
Warrant may be exercised, the Company will at all times have authorized, and
reserved for the purpose of the issuance upon exercise of the purchase rights
evidenced by this Warrant, a sufficient number of shares of its Common Stock to
provide for the exercise of the rights represented by this Warrant.

   5. Adjustment of Purchase Price and Number of Shares.

   The kind of securities purchasable upon the exercise of this Warrant, the
Warrant Price and the number of shares purchasable upon exercise of this
Warrant shall be subject to adjustment from time to time upon the occurrence of
the following events:
<PAGE>

     (a) Reclassification, Consolidation, or Merger. In case of any
  reclassification or change of outstanding securities of the class issuable
  upon exercise of this Warrant (other than a change in par value, or from
  par value to no par value, or from no par value to par value, or as a
  result of a subdivision or combination), or in case of any consolidation or
  merger of the Company with or into another corporation, other than a merger
  with another corporation in which the Company is a continuing corporation
  and which does not result in any reclassification or change of outstanding
  securities issuable upon exercise of this Warrant, the Company, or such
  successor, as the case may be, shall execute a new Warrant, providing that
  the Holder of this Warrant shall have the right to exercise such new
  Warrant and procure upon such exercise, in lieu of each share of Common
  Stock theretofore issuable upon exercise of this Warrant, the kind and
  amount of shares of stock, other securities, money and property receivable
  upon such reclassification, change, consolidation, or merger by a Holder of
  one share of Common Stock. Such new Warrant shall provide for adjustments,
  which shall be as nearly equivalent as may be practicable to the
  adjustments provided for in this Section 5. The provisions of this
  subparagraph (a) shall similarly apply to successive reclassification,
  changes, consolidations, and mergers.

     (b) Subdivision or Combination of Shares. If the Company at any time
  while this Warrant remains outstanding and unexpired shall subdivide or
  combine its common stock, or distribute dividends on its common stock
  payable in Common Stock, the Warrant Price shall be proportionately
  decreased in the case of a subdivision or increased in the case of a
  combination or dividend.

     (c) Adjustment of Number of Shares. Upon each adjustment in the Warrant
  Price pursuant to any of subparagraphs (a) through (c) of this Section 5,
  the number of shares of Common Stock purchasable hereunder shall be
  adjusted, to the nearest whole share, to the product obtained by
  multiplying the number of shares purchasable immediately prior to such
  adjustment in the Warrant Price by a fraction, the numerator of which shall
  be the Warrant Price immediately prior to such adjustment and the
  denominator of which shall be the Warrant Price immediately thereafter.

   6. Notice of Adjustments.

   Whenever any Warrant Price shall be adjusted pursuant to Section 5 hereof,
the Company shall prepare a certificate signed by its chief financial officer
setting forth, in reasonable detail, the event requiring the adjustment, the
amount of the adjustment, the method by which such adjustment was calculated,
the Warrant Price after giving effect to such adjustment and the number of
shares then purchasable upon exercise of this Warrant, and shall cause copies
of such certificate to be mailed (by first class mail, postage prepaid) to the
Holder of this Warrant at the address specified in Section 10(c) hereof, or at
such other address as may be provided to the Company in writing by the Holder
of this Warrant.

   7. Fractional Shares.

   No fractional shares of Common Stock will be issued in conjunction with any
exercise hereunder, but in lieu of such fractional shares the Company shall
make a cash payment therefor on the basis of the Warrant Price then in effect.
<PAGE>

   8. Compliance with Securities Act.

   The Holder of this Warrant, by acceptance hereof, agrees that this Warrant
and the shares of Common Stock to be issued on exercise hereof are being
acquired for investment and that it will not offer, sell or otherwise dispose
of this Warrant or any shares of Common Stock to be issued upon exercise hereof
except under circumstances which will not result in a violation of the
Securities Act of 1933, as amended (the "Act"). This Warrant and all shares of
Common Stock issued upon exercise of this Warrant (unless registered under the
Act) shall be stamped and imprinted with a legend substantially in the
following form:

     "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
  AS AMENDED (THE ACT"), OR APPLICABLE STATE SECURITIES LAWS AND MAY NOT BE
  TRANSFERRED OR OTHERWISE DISPOSED OF UNLESS IT HAS BEEN REGISTERED UNDER
  THE ACT AND SUCH LAWS OR (1) REGISTRATION UNDER SUCH LAWS IS NOT REQUIRED
  AND (2) AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY IS FURNISHED TO
  THE COMPANY TO THE EFFECT THAT REGISTRATION UNDER THE ACT AND THE
  APPLICABLE STATE SECURITIES LAWS IS NOT REQUIRED."

   9. Transfer and Exchange of Warrant.

   This Warrant is not transferable or exchangeable without the consent of the
Company.

   10. Miscellaneous.

     (a) No Rights as Shareholder. The Holder of this Warrant shall not be
  entitled to vote or receive dividends or be deemed the Holder of Common
  Stock or any other securities of the Company that may at any time be
  issuable on the exercise hereof for any purpose, nor shall anything
  contained herein be construed to confer upon the Holder of this Warrant, as
  such, any of the rights of a shareholder of the Company or any right to
  vote for the election of directors or upon any matter submitted to
  shareholders at any meeting thereof, or to give or withhold consent to any
  corporate action (whether upon any recapitalization, issuance of stock,
  reclassification of stock, change of par value or change of stock to no par
  value, consolidation, merger, conveyance or otherwise) or to receive notice
  of meetings, or to receive dividends or subscription rights or otherwise
  until the Warrant shall have been exercised and the shares purchasable upon
  the exercise hereof shall have become deliverable, as provided herein.

     (b) Replacement. On receipt of evidence reasonably satisfactory to the
  Company of the loss, theft, destruction, or mutilation of this Warrant and,
  in the case of mutilation, on surrender and cancellation of this Warrant,
  the Company, at its expense, will execute and deliver, in lieu of this
  Warrant, a new Warrant of like tenor.
<PAGE>

   (c) Notice. Any notice given to either party under this Warrant shall be in
writing, and any notice hereunder shall be deemed to have been given upon the
earlier of delivery thereof by hand delivery, by courier, or by standard form
of telecommunication or three (3) business days after the mailing thereof in
the U.S. mail if sent registered mail with postage prepaid, addressed to the
Company at its principal executive offices and to the Holder at its address set
forth in the Company's books and records or at such other address as the Holder
may have provided to the Company in writing.

   (d) Governing Law. This Warrant shall be governed and construed under the
laws of the State of California.

   This Warrant is executed as of this 21st day of July, 2000.

                                          ACACIA RESEARCH CORPORATION


                                          By: _________________________________
                                                      Victoria White
                                               Vice President, Legal Affairs
<PAGE>

                                   EXHIBIT 1

                               NOTICE OF EXERCISE

TO: ACACIA RESEARCH CORPORATION

   1. The undersigned hereby elects to purchase     shares of Common Stock of
Acacia Research Corporation pursuant to the terms of the attached Warrant, and
tenders herewith payment of the purchase price of such shares in full.

   2. Please issue a certificate or certificates representing said shares of
Common Stock in the name of the Holder at the address specified below:

    ---------------------------------------------------------------
    (Name)

    ---------------------------------------------------------------
    (Address)

    ---------------------------------------------------------------
    (Address)

   3. The undersigned represents that any of the aforesaid shares of Common
Stock not subject to an effective Registration Statement under the Securities
Act of 1933 are being acquired for the account of the undersigned for
investment and not with a view to, or for resale in connection with, the
distribution thereof and that the undersigned has no present intention of
distributing or reselling such shares.

   4. The undersigned represents that each of the representations and
warranties and each of the responses in the confidential purchaser
questionnaire given with the Subscription Agreement are true, correct and
complete as of the date hereof.

                                          -------------------------------------
                                          (Signature of Holder)

                                          -------------------------------------
                                          (Print Name of Holder)