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                                                                    Exhibit 10.5

                                [FORM OF WARRANT]

THE SECURITIES  REPRESENTED BY THIS WARRANT HAVE NOT BEEN  REGISTERED  UNDER THE
SECURITIES ACT OF 1933, AS AMENDED,  OR APPLICABLE  STATE  SECURITIES  LAWS. THE
SECURITIES  MAY NOT BE OFFERED FOR SALE,  SOLD,  TRANSFERRED  OR ASSIGNED IN THE
ABSENCE OF (A) AN EFFECTIVE  REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE
SECURITIES ACT OF 1933, AS AMENDED,  OR APPLICABLE  STATE SECURITIES LAWS OR (B)
AN OPINION OF COUNSEL, REASONABLY SATISFACTORY TO THE COMPANY, THAT REGISTRATION
IS NOT  REQUIRED  UNDER  SAID  ACT OR  APPLICABLE  STATE  SECURITIES  LAWS.  THE
SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER
LOAN SECURED BY THE SECURITIES.

                           HEMISPHERX BIOPHARMA, INC.

                        WARRANT TO PURCHASE COMMON STOCK

Warrant No.:  [  ]                                       Number of Shares:  [  ]
                                                         (subject to adjustment)

Date of Issuance:  March 12, 2003

      HEMISPHERX BIOPHARMA, INC., a Delaware corporation (the "Company"), hereby
certifies that, for Ten United States Dollars ($10.00) and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, ____________, the registered holder hereof or its permitted
assigns, is entitled, subject to the terms and conditions set forth below, to
purchase from the Company upon surrender of this Warrant, at any time or times
on or after the date hereof, but not after 11:59 P.M., New York City Time, on
the Expiration Date (as defined herein) 743,288 fully paid nonassessable shares
of Common Stock (as defined herein) of the Company at the Warrant Exercise Price
per share provided in Section 1(b) below. This Warrant shall be exercisable for
a number of Warrant Shares equal to: (i) prior to the Second Payment Date (as
defined in the Securities Purchase Agreement), 66.67% of the maximum number of
Warrant Shares issuable upon exercise of this Warrant; and (ii) after the Second
Payment Date, 100% of the maximum number of Warrant Shares issuable upon
exercise of this Warrant. Notwithstanding the foregoing, the Company shall not
effect the exercise of this Warrant and no holder of this Warrant shall have the
right to exercise this Warrant to the extent that after giving effect to such
exercise, such Person (together with such Person's affiliates), would have
acquired, through exercise of this Warrant or otherwise, beneficial ownership of
a number of shares of Common Stock that, when added to the number of shares of
Common Stock beneficially owned by such Person (together with such Person's
affiliates), exceeds 4.99% of the number of shares of Common Stock outstanding
immediately after giving effect to such exercise. For purposes of the foregoing
sentence, the aggregate number of shares of Common Stock beneficially owned by
such Person and its affiliates shall include the number of shares of Common
Stock issuable upon exercise of this Warrant with respect to which the
determination of such sentence is being made, but shall exclude shares of Common
Stock which would be issuable upon (i) exercise of the remaining,

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unexercised portion of this Warrant beneficially owned by such Person and its
affiliates and (ii) exercise or conversion of the unexercised or unconverted
portion of any other securities of the Company beneficially owned by such Person
and its affiliates (including, without limitation, any convertible notes,
debentures or preferred stock) subject to a limitation on conversion or exercise
analogous to the limitation contained herein. Except as set forth in the
preceding sentence, for purposes of this paragraph, beneficial ownership shall
be calculated in accordance with Section 13(d) of the Securities Exchange Act of
1934, as amended. Upon the written request of any holder, the Company shall
promptly, but in no event later than two (2) Business Days following the receipt
of such notice, confirm in writing to any such holder the number of shares of
Common Stock then outstanding. In any case, the number of outstanding shares of
Common Stock shall be determined after giving effect to the exercise of Warrants
(as defined below) by such holder and its affiliates since the date as of which
such number of outstanding shares of Common Stock was last reported.

      Section 1.

      a. SECURITIES PURCHASE AGREEMENT. This Warrant (as defined herein) is one
of a series of Warrants issued pursuant to Section 1 of that certain Securities
Purchase Agreement dated as of March 12, 2003, among the Company and the Persons
referred to therein, as such agreement may be amended from time to time as
provided in such agreement (the "Securities Purchase Agreement").

      b. DEFINITIONS. The location of definitions used in this Warrant is set
forth on the Index of Terms attached hereto and the following words and terms as
used in this Warrant shall have the following meanings:

            (i) "Approved Stock Plan" means any employee benefit plan, stock
incentive plan or other similar plan or arrangement which has been approved by
the Board of Directors of the Company or a duly authorized committee thereof,
pursuant to which the Company's securities may be issued to any employee,
consultant, officer or director for services provided to the Company.

            (ii) "Bloomberg" means Bloomberg Financial Markets or any other
similar financial reporting service as may be selected from time to time by the
Company and the holders of the Warrants representing not less than 60% of the
shares of Common Stock issuable upon exercise of all Warrants issued on the
Original Issuance Date then outstanding.

            (iii) "Business Day" means any day other than Saturday, Sunday or
other day on which commercial banks in The City of New York are authorized or
required by law to remain closed.

            (iv) "Closing Sale Price" means, for any security as of any date,
the last closing trade price for such security on the Principal Market as
reported by Bloomberg, or if the Principal Market begins to operate on an
extended hours basis, and does not designate the closing trade price, then the
last trade price at 4:00 p.m., New York City Time, as reported by Bloomberg, or
if the foregoing do not apply, the last closing trade price of such security in
the over-the-counter market on the electronic bulletin board for such security
as reported by


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Bloomberg, or, if no last closing trade price is reported for such security by
Bloomberg, the last closing ask price of such security as reported by Bloomberg,
or, if no last closing ask price is reported for such security by Bloomberg, the
average of the highest bid price and the lowest ask price of any market makers
for such security as reported in the "pink sheets" by the National Quotation
Bureau, Inc. If the Closing Sale Price cannot be calculated for such security on
such date on any of the foregoing bases, the Closing Sale Price of such security
on such date shall be the fair market value as mutually determined by the
Company and the holders of the Warrants representing at least 60% of the shares
of Common Stock obtainable upon exercise of all Warrants issued on the Original
Issuance Date then outstanding. If the Company and the holders of the Warrants
are unable to agree upon the fair market value of the Common Stock, then such
dispute shall be resolved pursuant to Section 2(a) below. All such
determinations shall be appropriately adjusted for any stock dividend, stock
split or other similar transaction during such period. All fees and expenses of
such determinations shall be borne solely by the Company.

            (v) "Common Stock" means (i) the Company's common stock, par value
$0.001 per share, and (ii) any capital stock into which such Common Stock shall
have been changed or any capital stock resulting from a reclassification of such
Common Stock.

            (vi) "Common Stock Deemed Outstanding" means, at any given time, the
number of shares of Common Stock actually outstanding at such time, plus the
number of shares of Common Stock deemed to be outstanding pursuant to Sections
8(b)(i) and 8(b)(ii) hereof regardless of whether the Options or Convertible
Securities are actually exercisable at such time, but excluding any shares of
Common Stock owned or held by or for the account of the Company or issuable upon
conversion of the Convertible Debentures or exercise of the Warrants.

            (vii) "Convertible Debentures" means all of the Company's 6% Senior
Secured Convertible Debentures Due January 31, 2005 issued pursuant to the
Securities Purchase Agreement.

            (viii) "Convertible Securities" means any stock or securities (other
than Options) directly or indirectly convertible into or exchangeable or
exercisable for Common Stock.

            (ix) "Expiration Date" means March 12, 2008 or, if such date does
not fall on a Business Day or on a day on which trading takes place on the
Principal Market, then the next Business Day.

            (x) "Initial Warrant Exercise Price" shall be equal to $1.68,
subject to further adjustment as provided in Section 8, Adjustment of Warrant
Exercise Price and Number of Shares.

            (xi) "Option" means any rights, warrants or options to subscribe for
or purchase or otherwise acquire Common Stock or Convertible Securities.

            (xii) "Original Issuance Date" means the first date on which any
Warrants have been issued pursuant to the Securities Purchase Agreement.


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            (xiii) "Person" means an individual, a limited liability company, a
partnership, a joint venture, a corporation, a trust, an unincorporated
organization and a government or any department or agency thereof.

            (xiv) "Principal Market" means The American Stock Exchange ("Amex")
or if the Common Stock is not traded on Amex then the principal securities
exchange or trading market for the Common Stock.

            (xv) "Registration Rights Agreement" means that registration rights
agreement dated March 12, 2003 by and among the Company and the Persons referred
to therein, as such agreement may be amended from time to time as provided in
such agreement.

            (xvi) "Reset Warrant Exercise Price" shall mean the greater of (x)
the arithmetic average of the Weighted Average Price of the Common Stock for
each trading date beginning on the first trading date immediately following the
Original Issuance Date and ending on the final trading date immediately prior to
the one-year anniversary of the Original Issuance Date (which Weighted Average
Price on each such trading date during such period shall be appropriately
adjusted for any stock dividend, stock split or other similar transaction during
such period) and (y) 70% of the Initial Warrant Exercise Price (appropriately
adjusted for any stock dividend, stock split or other similar transaction during
such period).

            (xvii) "Securities Act" means the Securities Act of 1933, as
amended.

            (xviii) "Strategic Financing" shall mean the issuance of Common
Stock or Options in connection with any acquisition by the Company, by whatever
means, of any business, assets or technologies, or to any strategic investor,
vendor, customer, lease or similar arrangement, the primary purpose of which is
not to raise equity capital, provided that the aggregate number of shares of
Common Stock which the Company may issue pursuant to this definition shall not
exceed (i) 25% of the total outstanding equity on the Closing Date (as defined
in the Securities Purchase Agreement) in connection with any one or more related
issuances to strategic investors, vendors, customers, lessors or similar parties
or (ii) 40% of the total outstanding equity on the Closing Date (as defined in
the Securities Purchase Agreement) in connection with all issuances to strategic
investors, vendors, customers, lessors or similar parties (in each case, subject
to adjustment for stock splits, stock dividends, stock combination and similar
transactions).

            (xix) "Warrant" means the warrants to purchase shares of Common
Stock issued pursuant to the Securities Purchase Agreement and all warrants
issued in exchange, transfer or replacement thereof.

            (xx) "Warrant Exercise Price" shall be equal to: (i) from the
Original Issuance Date until the date immediately prior to the one-year
anniversary of the Original Issuance Date, the Initial Warrant Exercise Price,
and (ii) from and after such one-year anniversary, the lesser of (x) the Initial
Warrant Exercise Price and (y) the Reset Warrant Exercise Price, in each case
appropriately adjusted for any stock dividend, stock split or other similar
transaction during such period. The Warrant Exercise Price shall be subject to
further


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adjustment as provided in Section 8, Adjustment of Warrant Exercise Price and
Number of Shares.

            (xxi) "Warrant Shares" means all shares of Common Stock issuable
upon exercise of the Warrants.

            (xxii) "Weighted Average Price" shall mean, for any security as of
any date, the dollar volume-weighted average price per share for such security
on the Principal Market during the period beginning at 9:30 a.m., New York City
Time, and ending at 4:00 p.m., New York City Time, as reported by Bloomberg
through its "Volume at Price" function or, if the foregoing does not apply, the
dollar volume-weighted average price per share of such security in the
over-the-counter market on the electronic bulletin board for such security
during the period beginning at 9:30 a.m., New York City Time, and ending at 4:00
p.m., New York City Time, as reported by Bloomberg, or, if no dollar
volume-weighted average price is reported for such security by Bloomberg for
such hours, the average of the highest closing bid price and the lowest closing
ask price of any of the market makers for such security as reported in the "pink
sheets" by the National Quotation Bureau, Inc. If the Weighted Average Price
cannot be calculated for such security on such date on any of the foregoing
bases, the Weighted Average Price of such security on such date shall be the
fair market value as mutually determined by the Company and the holders of the
Warrants representing at least 60% of the shares of Common Stock obtainable upon
exercise of the Warrants issued on the Original Issuance Date then outstanding.
If the Company and the holders of the Warrants are unable to agree upon the fair
market value of the Common Stock, then such dispute shall be resolved pursuant
to Section 2(a) below with the term "Weighted Average Price" being substituted
for the term "Closing Sale Price." All such determinations shall be
appropriately adjusted for any stock dividend, stock split or other similar
transaction during such period. All fees and expenses of such determinations
shall be borne solely by the Company.

      Section 2. EXERCISE OF WARRANT.

      a. Subject to the terms and conditions hereof, this Warrant may be
exercised by the holder hereof then registered on the books of the Company, in
whole or in part, at any time on any Business Day on or after the opening of
business on the date hereof and prior to 5:00 P.M., New York City Time, on the
Expiration Date by (i) delivery of a written notice, in the form of the
subscription notice attached as EXHIBIT A hereto or a reasonable facsimile
thereof (the "Exercise Notice"), to the Company and the Company's designated
transfer agent (the "Transfer Agent"), of such holder's election to exercise
this Warrant, which notice shall specify the number of Warrant Shares to be
purchased, (ii)(A) payment to the Company of an amount equal to the Warrant
Exercise Price multiplied by the number of Warrant Shares as to which this
Warrant is being exercised (the "Aggregate Exercise Price") in cash or delivery
of a certified check or bank draft payable to the order of the Company or wire
transfer of immediately available funds or (B) by notifying the Company that
this Warrant is being exercised pursuant to a Cashless Exercise (as defined in
Section 2(e)), and (iii) the surrender of this Warrant or a copy of this Warrant
(provided it is accompanied by an indemnification undertaking with respect to
this Warrant in the case of its loss, theft or destruction) to a common carrier
for overnight delivery to the Company or by delivery of a facsimile copy of this
Warrant to the Company as soon as practicable following such date; provided,
that if such Warrant Shares are to be issued in


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any name other than that of the registered holder of this Warrant, such issuance
shall be deemed a transfer and the provisions of Section 7 shall be applicable.
In the event of any exercise of the rights represented by this Warrant in
compliance with this Section 2(a), the Company shall on the second (2nd)
Business Day (the "Warrant Share Delivery Date") following the date of its
receipt of the Exercise Notice, the Aggregate Exercise Price (or notice of
Cashless Exercise) and the original or a copy of this Warrant (provided it is
accompanied by an indemnification undertaking or other form of security
reasonably satisfactory to the Company with respect to this Warrant in the case
of its loss, theft or destruction) (collectively, the "Exercise Delivery
Documents"), (A) in the case of a public resale of such Warrant Shares in
accordance with the provisions of the Irrevocable Transfer Agent Instructions,
provided the Transfer Agent is participating in The Depository Trust Company
("DTC") Fast Automated Securities Transfer Program and, if required by DTC, the
holder provides a customary representation letter to DTC, at the holder's
request, credit such aggregate number of shares of Common Stock to which the
holder shall be entitled to the holder's or its designee's balance account with
DTC through its Deposit Withdrawal Agent Commission system or (B) issue and
deliver to the address as specified in the Exercise Notice, a certificate or
certificates in such denominations as may be requested by the holder in the
Exercise Notice, registered in the name of the holder or its designee, for the
number of shares of Common Stock to which the holder shall be entitled upon such
exercise. Upon delivery of the Exercise Delivery Documents, the holder of this
Warrant shall be deemed for all corporate purposes to have become the holder of
record of the Warrant Shares with respect to which this Warrant has been
exercised, irrespective of the date of delivery of this Warrant as required by
clause (iii) above or the certificates evidencing such Warrant Shares. In the
case of a dispute as to the determination of the Warrant Exercise Price, the
Closing Sale Price of a security or the arithmetic calculation of the number of
Warrant Shares, the Company shall promptly issue to the holder the number of
shares of Common Stock that is not disputed and shall submit the disputed
determinations or arithmetic calculations to the holder via facsimile within two
(2) Business Days of receipt of the holder's Exercise Notice. If the holder and
the Company are unable to agree upon the determination of the Warrant Exercise
Price, the Closing Sale Price or arithmetic calculation of the number of Warrant
Shares within one (1) Business Day of such disputed determination or arithmetic
calculation being submitted to the holder, then the Company shall immediately
submit via facsimile (i) the disputed determination of the Warrant Exercise
Price or the Closing Sale Price to an independent, reputable investment banking
firm selected jointly by the Company and the holder or (ii) the disputed
arithmetic calculation of the number of Warrant Shares to its independent,
outside accountant. The Company shall cause the investment banking firm or the
accountant, as the case may be, to perform the determinations or calculations
and notify the Company and the holder of the results no later than ten (10)
Business Days from the time it receives the disputed determinations or
calculations. Such investment banking firm's or accountant's determination or
calculation, as the case may be, shall be deemed conclusive absent manifest
error.

      b. Unless the rights represented by this Warrant shall have expired or
shall have been fully exercised (without regard to any limitation on exercise
hereunder), the Company shall, as soon as practicable using reasonable best
efforts and in no event later than five (5) Business Days after its receipt of
the Exercise Delivery Documents (the "Warrant Delivery Date") and at its own
expense, issue a new Warrant identical in all respects to this Warrant exercised
except it shall represent rights to purchase the number of Warrant Shares
purchasable (without regard to


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any limitation on exercise hereunder) immediately prior to such exercise under
this Warrant, less the number of Warrant Shares with respect to which such
Warrant is exercised.

      c. No fractional shares of Common Stock are to be issued upon the exercise
of this Warrant, but rather the number of shares of Common Stock issued upon
exercise of this Warrant shall be rounded up or down to the nearest whole
number.

      d. If the Company shall fail for any reason or for no reason to issue to
the holder within five (5) Business Days of receipt of the Exercise Delivery
Documents, a certificate for the number of shares of Common Stock to which the
holder is entitled or to credit the holder's designee's balance account with
DTC, in accordance with Section 2 hereof, for such number of shares of Common
Stock to which the holder is entitled upon the holder's exercise of this
Warrant, the Company shall, in addition to any other remedies under this Warrant
or the Securities Purchase Agreement or otherwise available to such holder,
including any indemnification under Section 8 of the Securities Purchase
Agreement, pay as additional damages in cash to such holder on each day after
the Warrant Share Delivery Date such exercise is not timely effected in an
amount equal to 0.05% multiplied by the product of (I) the sum of the number of
shares of Common Stock not issued to the holder on or prior to the Warrant Share
Delivery Date and to which such holder is entitled under the holder's Exercise
Notice and (II) the excess of the Closing Sale Price of the Common Stock on the
Warrant Share Delivery Date over the Warrant Exercise Price then in effect. The
foregoing notwithstanding, the damages set forth in this Section 2(d) shall be
stayed with respect to the number of shares of Common Stock for which there is a
good faith dispute being resolved pursuant to, and within the time periods
provided for in, Section 2(a), pending the resolution of such dispute.

      e. Notwithstanding anything contained herein to the contrary, if at any
time during the two (2) Business Day period immediately preceding the holder's
delivery of an Exercise Notice, a Registration Statement (as defined in the
Registration Rights Agreement) covering the Warrant Shares that are the subject
of the Exercise Notice (the "Unavailable Warrant Shares") is not available for
the resale of such Unavailable Warrant Shares, the holder of this Warrant may,
at its election exercised in its sole discretion, exercise this Warrant as to
any or all of such Unavailable Warrant Shares and, in lieu of making the cash
payment otherwise contemplated to be made to the Company upon such exercise in
payment of the Aggregate Exercise Price, elect instead to receive upon such
exercise the "Net Number" of shares of Common Stock determined according to the
following formula (a "Cashless Exercise"):

      Net Number =   (A x B) - (A x C)
                    -------------------
                             B

      For purposes of the foregoing formula:

      A= the total number of shares with respect to which this Warrant is then
      being exercised.

      B= the Closing Sale Price of the Common Stock on the trading day
      immediately preceding the date of the Exercise Notice.


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      C= the Warrant Exercise Price then in effect for the applicable Warrant
      Shares at the time of such exercise.

      Section 3. COVENANTS AS TO COMMON STOCK. The Company hereby covenants and
agrees as follows:

      a. This Warrant is, and any Warrants issued in substitution for or
replacement of this Warrant will upon issuance be, duly authorized and validly
issued.

      b. All Warrant Shares which may be issued upon the exercise of the rights
represented by this Warrant will, upon issuance and payment hereof in accordance
with the terms hereof, be validly issued, fully paid and nonassessable and free
from all taxes, liens and charges created by or through the Company with respect
to the issue thereof.

      c. During the period within which the rights represented by this Warrant
may be exercised, the Company will at all times have authorized and reserved at
least 135% of the number of shares of Common Stock needed to provide for the
exercise of the rights then represented by this Warrant (without regard to any
limitation on exercise hereunder)and the par value of said shares will at all
times be less than or equal to the applicable Warrant Exercise Price.

      d. The Company shall promptly secure the listing of the shares of Common
Stock issuable upon exercise of this Warrant (without regard to any limitation
on exercise hereunder) upon each national securities exchange or automated
quotation system, if any, upon which shares of Common Stock are then listed
(subject to official notice of issuance upon exercise of this Warrant) and shall
maintain, so long as any other shares of Common Stock shall be so listed, such
listing of all shares of Common Stock from time to time issuable upon the
exercise of this Warrant (without regard to any limitation on exercise
hereunder); and the Company shall so list on each national securities exchange
or automated quotation system, as the case may be, and shall maintain such
listing of, any other shares of capital stock of the Company issuable upon the
exercise of this Warrant (without regard to any limitation on exercise
hereunder) if and so long as any shares of the same class shall be listed on
such national securities exchange or automated quotation system.

      e. The Company will not, by amendment of its Articles of Incorporation or
through any reorganization, transfer of assets, consolidation, merger,
dissolution, issue or sale of securities, or any other voluntary action, avoid
or seek to avoid the observance or performance of any of the terms to be
observed or performed by it hereunder. Without limiting the generality of the
foregoing, the Company (i) will not increase the par value of any shares of
Common Stock receivable upon the exercise of this Warrant above the Warrant
Exercise Price then in effect, (ii) will take all such actions as may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and nonassessable shares of Common Stock upon the exercise of this
Warrant and (iii) will not take any action which results in any adjustment of
the Warrant Exercise Price if the total number of shares of Common Stock
issuable after the action upon the exercise of all of the Warrants would exceed
the total number of shares of Common Stock then authorized by the Company's
Articles of Incorporation and available for the purpose of issue upon such
exercise.


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      f. This Warrant will be binding upon any entity succeeding to the Company
by merger, consolidation or acquisition of all or substantially all of the
Company's assets.

      Section 4. TAXES. a. The Company shall pay any and all documentary, stamp,
transfer and other similar taxes which may be payable with respect to the
issuance and delivery of Warrant Shares upon exercise of this Warrant; provided,
however, that the Company shall not be required to pay any tax that may be
payable in respect of any transfer involved in the issue or delivery of Common
Stock or other securities or property in a name other than that of the
registered holder of this Warrant to be exercised and such holder shall pay such
amount, if any, to cover any applicable transfer or similar tax.

      b. The Company and the Company's transfer agent shall be permitted to
withhold from any amounts payable to a registered holder of this Warrant or any
holder of Warrant Shares any taxes required by law to be withheld from such
amounts.

      c. Notwithstanding any other provision of this Agreement or any other
Transaction Document, any assignee or transferee shall agree that the Company
and the Company's transfer agent shall be permitted to withhold from any amounts
payable to such assignee or transferee any taxes required by law to be withheld
from such amounts. Unless exempt from the obligation to do so, each assignee or
transferee shall execute and deliver to the Company or the Company's transfer
agent, as applicable, two properly completed and duly executed copies of either
(i) U.S. Internal Revenue Service Form W-8BEN, or any successor form, (ii) U.S.
Internal Revenue Service Form W-8ECI, or any successor form, (iii) U.S. Internal
Revenue Service Form W-9, or any successor form, or (iv) other applicable form,
certificate or document prescribed by the U.S. Internal Revenue Service, as
applicable, in each case, indicating that such assignee or transferee is not
subject to "back-up withholding" for U.S. Federal income tax purposes. Each
assignee or transferee that does not deliver such forms pursuant to the
preceding sentence shall have the burden of proving to the Company's reasonable
satisfaction that it is exempt from such requirement or the Company and the
Company's transfer agent shall be entitled to withhold as provided in the first
sentence hereof. In addition, each assignee or transferee that is organized
under the laws of a jurisdiction other than the United States, any State thereof
or the District of Columbia (each, a "Non-U.S. Assignee or Transferee") shall
deliver to the Company and the Company's transfer agent, to the extent legally
able to do so, with respect to payments of dividends by the Company for U.S.
Federal income tax purposes, if applicable, two properly completed and duly
executed copies of either (i) U.S. Internal Revenue Service Form W-8BEN
(claiming a reduction of U.S. Federal withholding tax under an applicable income
tax treaty, if any), or any successor form, (ii) U.S. Internal Revenue Service
Form W-8ECI (claiming complete exemption from U.S. Federal withholding tax
because the income is effectively connected with a U.S. trade or business), or
any successor form, or (iii) other applicable form, certificate or document
prescribed by the U.S. Internal Revenue Service certifying as to such assignee's
or transferee's entitlement to an exemption from, or a reduction of, U.S.
Federal withholding tax on payments of dividends by the Company for U.S. Federal
income tax purposes. Each Non-U.S. Assignee or Transferee that does not deliver
a form or other document claiming a complete exemption from U.S. Federal
withholding tax shall have the burden of proving to the Company's reasonable
satisfaction that it is completely exempt from such tax or the Company and the
Company's transfer agent shall be entitled to withhold as provided in the second
sentence of this Section 4(c). The forms and other documents required to


                                       9
<PAGE>

be delivered pursuant to this Section 4 shall be properly completed and duly
executed and shall be delivered on or prior to the date of such assignment or
transfer, and from time to time thereafter if requested by the Company or the
Company's transfer agent. In addition, each assignee and transferee shall
deliver such forms and other documents promptly upon the obsolescence or
invalidity of any form or documents previously delivered by such assignee or
transferee. Each assignee and transferee shall promptly notify the Company and
the Company's transfer agent at any time it determines that it is no longer in a
position to provide any previously delivered form, document or certificate to
the Company and the Company's transfer agent (or any form of certification
adopted by the U.S. taxing authorities for such purpose).

      Section 5. WARRANT HOLDER NOT DEEMED A STOCKHOLDER. Except as otherwise
specifically provided herein, no holder, as such, of this Warrant shall be
entitled to vote or receive dividends or be deemed the holder of shares of the
Company for any purpose, nor shall anything contained in this Warrant be
construed to confer upon the holder hereof, as such, any of the rights of a
stockholder of the Company or any right to vote, give or withhold consent to any
corporate action (whether any reorganization, issue of stock, reclassification
of stock, consolidation, merger, conveyance or otherwise), receive notice of
meetings, receive dividends or subscription rights, or otherwise, prior to the
issuance to the holder of this Warrant of the Warrant Shares which he, she, or
it is then entitled to receive upon the due exercise of this Warrant. In
addition, nothing contained in this Warrant shall be construed as imposing any
liabilities on such holder to purchase any securities (upon exercise of this
Warrant or otherwise) or as a stockholder of the Company, whether such
liabilities are asserted by the Company or by creditors of the Company.

      Section 6. REPRESENTATIONS OF HOLDER. The holder of this Warrant, by the
acceptance hereof, represents and warrants that it is acquiring this Warrant,
and the Warrant Shares for its own account for investment only and not with a
view towards, or for sale in connection with, the public sale or distribution of
this Warrant or the Warrant Shares, except pursuant to sales registered or
exempted under the Securities Act; provided, however, that by making the
representations herein, the holder does not agree to hold this Warrant or any of
the Warrant Shares for any minimum or other specific term and reserves the right
to dispose of this Warrant and the Warrant Shares at any time in accordance with
or pursuant to a registration statement or an exemption under the Securities
Act. The holder of this Warrant further represents, by acceptance hereof, that,
as of this date, such holder is an "accredited investor" as such term is defined
in Rule 501(a) of Regulation D promulgated by the Securities and Exchange
Commission under the Securities Act (an "Accredited Investor").

      Section 7. OWNERSHIP AND TRANSFER.

      a. The Company shall maintain at its principal executive offices (or such
other office or agency of the Company as it may designate by notice to the
holder hereof), a register for this Warrant, in which the Company shall record
the name and address of the person in whose name this Warrant has been issued,
as well as the name and address of each transferee. The Company may treat the
person in whose name any Warrant is registered on the register as the owner and
holder thereof for all purposes, notwithstanding any notice to the contrary, but
in all events recognizing any transfers made in accordance with the terms of
this Warrant.


                                       10
<PAGE>

      b. This Warrant and all rights hereunder shall be assignable and
transferable by the holder hereof without the consent of the Company upon
surrender of this Warrant with a properly executed assignment (in the form of
Exhibit B hereto) at the principal executive offices of the Company (or such
other office or agency of the Company as it may designate in writing to the
holder hereof); provided, that (x) either (i) the Warrant shall have been
registered under the Securities Act or (ii) the Company first shall have been
furnished with an opinion of counsel, in a form reasonably satisfactory to the
Company, to the effect that such sale or transfer is exempt from the
registration requirements of the Securities Act and (y) such transfer or
assignment of this Warrant does not result in more than ten (10) holders of all
outstanding Warrants and any such part or portion of this Warrant constitutes at
least 10% of the number of Warrant Shares issuable upon exercise of all
outstanding Warrants (subject to appropriate adjustment for stock splits, stock
dividends, combinations, recapitalizations and other similar transactions) or
such lesser number if such transfer involves all of the Warrant Shares
represented by the Warrants then held by such transferor.

      c. The Company is obligated to register the Warrant Shares for resale
under the Securities Act pursuant to the Registration Rights Agreement. The
shares of Common Stock issuable upon exercise of this Warrant shall constitute
Registrable Securities (as such term is defined in the Registration Rights
Agreement). Each holder of this Warrant shall be entitled to all of the benefits
afforded to a holder of any such Registrable Securities under the Registration
Rights Agreement and such holder, by its acceptance of this Warrant, agrees and
shall agree to be bound by and to comply with the terms and conditions of the
Registration Rights Agreement applicable to such holder as a holder of such
Registrable Securities.

      Section 8. ADJUSTMENT OF WARRANT EXERCISE PRICE AND NUMBER OF SHARES. The
Warrant Exercise Price and the number of shares of Common Stock issuable upon
exercise of this Warrant shall be adjusted from time to time as follows:

      a. ADJUSTMENT OF WARRANT EXERCISE PRICE. If and whenever on or after the
Warrant Date and prior to the twelve (12) month anniversary of the Warrant Date,
the Company issues or sells, or is deemed to have issued or sold, any shares of
Common Stock (including the issuance or sale of shares of Common Stock owned or
held by or for the account of the Company, but excluding shares of Common Stock
(i) issued or deemed to have been issued by the Company in connection with an
Approved Stock Plan, (ii) issued or deemed to have been issued upon exercise of
the Warrants or issued upon the issuance or conversion of the Convertible
Debentures; (iii) issued upon exercise of Options or Convertible Securities
which are outstanding on the date immediately preceding the Warrant Date,
provided that such issuance of shares of Common Stock upon exercise of such
Options or Convertible Securities is made pursuant to the terms of such Options
or Convertible Securities in effect on the date immediately preceding the
Warrant Date and such Options or Convertible Securities are not amended after
the date immediately preceding the Warrant Date other than with respect to
Options originally issued pursuant to an Approved Stock Plan, (iv) issued
pursuant to a Strategic Financing; or (v) issued to the public pursuant to an
underwritten offering registered pursuant to the Securities Act (but in all
events excluding offerings pursuant to "equity lines" or similar products) ((i)
through (v) collectively, "Excluded Issuances")) for a consideration per share
(the "New Issuance Price") less than the Warrant Exercise Price in effect
immediately prior to such issuance or sale (each such sale or issuance, a
"Dilutive Issuance"), then concurrent with such issue or sale, the Warrant


                                       11
<PAGE>

Exercise Price then in effect shall be reduced to a price (subject to Section
8(f)) equal to the New Issuance Price. If and whenever on or after the twelve
(12) month anniversary of the Warrant Date and prior to the Expiration Date, the
Company issues or sells, or is deemed to have issued or sold, any shares of
Common Stock (including the issuance or sale of shares of Common Stock owned or
held by or for the account of the Company, but excluding shares of Common Stock
issued or deemed to be issued pursuant to any Excluded Issuance) in a Dilutive
Issuance, then concurrent with such issue or sale, the Warrant Exercise Price
then in effect shall be reduced to a price (rounded to the nearest cent) equal
to the product of (x) the Warrant Exercise Price in effect immediately prior to
such issuance or sale and (y) the quotient determined by dividing (1) the sum of
(I) the product derived by multiplying the Warrant Exercise Price in effect
immediately prior to such Dilutive Issuance by the number of shares of Common
Stock Deemed Outstanding immediately prior to such issue or sale, plus (II) the
consideration, if any, received by the Company upon such Dilutive Issuance, by
(2) the product derived by multiplying the (I) the Warrant Exercise Price in
effect immediately prior to such Dilutive Issuance by (II) the number of shares
of Common Stock Deemed Outstanding immediately after such Dilutive Issuance.

      b. EFFECT ON WARRANT EXERCISE PRICE OF CERTAIN EVENTS. For purposes of
determining the adjusted Warrant Exercise Price under Section 8(a) above, the
following shall be applicable:

            (i) ISSUANCE OF OPTIONS. If the Company in any manner grants any
Options and the lowest price per share for which one share of Common Stock is
issuable upon the exercise of any such Option or upon conversion, exchange or
exercise of any Convertible Securities issuable upon exercise of any such Option
is less than the Warrant Exercise Price in effect immediately prior to such
Dilutive Issuance, then such share of Common Stock shall be deemed to be
outstanding and to have been issued and sold by the Company at the time of the
granting or sale of such Option for such price per share. For purposes of this
Section 8(b)(i), the "lowest price per share for which one share of Common Stock
is issuable upon exercise of any such Option or upon conversion, exchange or
exercise of any Convertible Securities issuable upon exercise of any such
Option" shall be equal to the sum of the lowest amounts of consideration (if
any) received or receivable by the Company with respect to any one share of
Common Stock upon the granting or sale of the Option, upon exercise of the
Option and upon conversion, exchange or exercise of any Convertible Security
issuable upon exercise of such Option. No further adjustment of the Warrant
Exercise Price shall be made upon the actual issuance of such Common Stock or of
such Convertible Securities upon the exercise of such Options or upon the actual
issuance of such Common Stock upon conversion, exchange or exercise of such
Convertible Securities.

            (ii) ISSUANCE OF CONVERTIBLE SECURITIES. If the Company in any
manner issues or sells any Convertible Securities and the lowest price per share
for which one share of Common Stock is issuable upon such conversion, exchange
or exercise thereof is less than the Warrant Exercise Price in effect
immediately prior to such Dilutive Issuance, then such share of Common Stock
shall be deemed to be outstanding and to have been issued and sold by the
Company at the time of the issuance or sale of such Convertible Securities for
such price per share. For the purposes of this Section 8(b)(ii), the "lowest
price per share for which one share of Common Stock is issuable upon such
conversion, exchange or exercise" shall be equal to the sum of the lowest
amounts of consideration (if any) received or receivable by the


                                       12
<PAGE>

Company with respect to one share of Common Stock upon the issuance or sale of
the Convertible Security and upon conversion, exchange or exercise of such
Convertible Security. No further adjustment of the Warrant Exercise Price shall
be made upon the actual issuance of such Common Stock upon conversion, exchange
or exercise of such Convertible Securities, and if any such issue or sale of
such Convertible Securities is made upon exercise of any Options for which
adjustment of the Warrant Exercise Price had been or are to be made pursuant to
other provisions of this Section 8(b), no further adjustment of the Warrant
Exercise Price shall be made by reason of such issue or sale.

            (iii) CHANGE IN OPTION PRICE OR RATE OF CONVERSION. If the purchase
or exercise price provided for in any Options, the additional consideration, if
any, payable upon the issue, conversion, exchange or exercise of any Convertible
Securities, or the rate at which any Convertible Securities are convertible into
or exchangeable or exercisable for Common Stock changes at any time, the Warrant
Exercise Price in effect at the time of such change shall be adjusted to the
Warrant Exercise Price which would have been in effect at such time had such
Options or Convertible Securities provided for such changed purchase price,
additional consideration or changed conversion rate, as the case may be, at the
time initially granted, issued or sold and the number of shares of Common Stock
acquirable hereunder shall be correspondingly readjusted. For purposes of this
Section 8(b)(iii), if the terms of any Option or Convertible Security that was
outstanding as of the date of issuance of this Warrant are changed in the manner
described in the immediately preceding sentence, then such Option or Convertible
Security and the Common Stock deemed issuable upon conversion, exchange or
exercise thereof shall be deemed to have been issued as of the date of such
change. No adjustment shall be made if such adjustment would result in an
increase of the Warrant Exercise Price then in effect.

      c. HOLDER'S RIGHT OF ALTERNATIVE WARRANT EXERCISE PRICE FOLLOWING ISSUANCE
OF CONVERTIBLE SECURITIES. If the Company issues or sells any Options or
Convertible Securities after the Closing Date that are convertible into or
exchangeable or exercisable for Common Stock at a price which varies or may vary
with the market price of the Common Stock, including by way of one or more
reset(s) to a fixed price (each of the formulations for such variable price
being herein referred to as, the "Variable Price"), the Company shall provide
written notice thereof via facsimile and overnight courier to the holder of this
Warrant (the "Variable Notice") on the date of issuance of such Convertible
Securities or Options. From and after the date the Company issues any such
Convertible Securities or Options with a Variable Price, but only for so long as
such Convertible Securities or Options are outstanding, the holder shall have
the right, but not the obligation, in its sole discretion to substitute the
Variable Price for the Warrant Exercise Price upon exercise of this Warrant by
designating in the Exercise Notice delivered upon exercise of this Warrant that
solely for purposes of such exercise the holder is relying on the Variable Price
rather than the Warrant Exercise Price then in effect. The holder's election to
rely on a Variable Price for a particular exercise of this Warrant shall not
obligate the holder to rely on a Variable Price for any future exercises of this
Warrant.

      d. EFFECT ON WARRANT EXERCISE PRICE OF CERTAIN EVENTS. For purposes of
determining the adjusted Warrant Exercise Price under Sections 8(a) and 8(b),
the following shall be applicable:


                                       13
<PAGE>

            (i) CALCULATION OF CONSIDERATION RECEIVED. In case any Option is
issued in connection with the issue or sale of other securities of the Company,
together comprising one integrated transaction in which no specific
consideration is allocated to such Options by the parties thereto, then, solely
for the purposes of this Section 8, the Options will be deemed to have been
issued for a consideration of $0.01. If any Common Stock, Options or Convertible
Securities are issued or sold or deemed to have been issued or sold for cash,
the consideration received therefor will be deemed to be the gross amount
received by the Company therefor. If any Common Stock, Options or Convertible
Securities are issued or sold for a consideration other than cash, the amount of
such consideration received by the Company will be the fair value of such
consideration, except where such consideration consists of marketable
securities, in which case the amount of consideration received by the Company
will be the Closing Sale Price of such securities on the date of receipt of such
securities. If any Common Stock, Options or Convertible Securities are issued to
the owners of the non-surviving entity in connection with any merger in which
the Company is the surviving entity, the amount of consideration therefor will
be deemed to be the fair value of such portion of the net assets and business of
the non-surviving entity as is attributable to such Common Stock, Options or
Convertible Securities, as the case may be. The fair value of any consideration
other than cash or securities will be determined by the Company and the holders
of Warrants representing at least 60% of the shares of Common Stock obtainable
upon exercise of all Warrants issued on the Original Issuance Date then
outstanding. If such parties are unable to reach agreement within ten (10) days
after the occurrence of an event requiring valuation (the "Valuation Event"),
the fair value of such consideration will be determined within five (5) Business
Days after the tenth (10th) day following the Valuation Event by an independent,
reputable appraiser jointly selected by the Company and the holders of the
Warrants representing at least 60% of the shares of Common Stock obtainable upon
exercise of all Warrants issued on the Original Issuance Date then outstanding.
The determination of such appraiser shall be final and binding upon all parties
absent manifest error and the fees and expenses of such appraiser shall be borne
by the Company.

            (ii) RECORD DATE. If the Company takes a record of the holders of
Common Stock for the purpose of entitling them (1) to receive a dividend or
other distribution payable in Common Stock, Options or in Convertible Securities
or (2) to subscribe for or purchase Common Stock, Options or Convertible
Securities, then such record date will be deemed to be the date of the issue or
sale of the shares of Common Stock deemed to have been issued or sold upon the
declaration of such dividend or the making of such other distribution or the
date of the granting of such right of subscription or purchase, as the case may
be. If after the occurrence of such record date the transaction or event for
which such record date was set is abandoned or terminated, then any adjustments
resulting from this Section 8(d)(ii) as it relates to such terminated or
abandoned transaction or event shall be reversed as if such record date had
never occurred.

      e. ADJUSTMENT OF WARRANT EXERCISE PRICE AND NUMBER OF SHARES UPON
SUBDIVISION OR COMBINATION OF COMMON STOCK. If the Company at any time after the
date of issuance of this Warrant subdivides (by any stock split, stock dividend,
recapitalization or otherwise) one or more classes of its outstanding shares of
Common Stock into a greater number of shares, the Warrant Exercise Price in
effect immediately prior to such subdivision will be proportionately reduced and
the number of shares of Common


                                       14
<PAGE>

Stock obtainable upon exercise of this Warrant will be proportionately
increased. If the Company at any time after the date of issuance of this Warrant
combines (by combination, reverse stock split or otherwise) one or more classes
of its outstanding shares of Common Stock into a smaller number of shares, the
Warrant Exercise Price in effect immediately prior to such combination will be
proportionately increased and the number of shares of Common Stock obtainable
upon exercise of this Warrant will be proportionately decreased. Any adjustment
under this Section 8(e) shall become effective at the close of business on the
date the subdivision or combination becomes effective.

      f. CERTAIN EVENTS. If any event occurs of the type contemplated by the
provisions of this Section 8 in a private transaction (the primary purpose of
which is to raise equity capital) but not expressly provided for by such
provisions (including, without limitation, the granting of stock appreciation
rights, phantom stock rights or other rights with equity features other than
pursuant to an Excluded Issuance), then the Company's Board of Directors will
make an appropriate adjustment in the Warrant Exercise Price and the number of
shares of Common Stock obtainable upon exercise of this Warrant so as to protect
the rights of the holders of the Warrants; provided that no such adjustment will
increase the Warrant Exercise Price or decrease the number of shares of Common
Stock obtainable as otherwise determined pursuant to this Section 8.

      g. NOTICES.

            (i) Promptly following any adjustment of the Warrant Exercise Price,
the Company will give written notice thereof to the holder of this Warrant,
setting forth in reasonable detail, and certifying, the calculation of such
adjustment. The Company (at the Company's expense), if there shall be a
disagreement among the Company and holders of Warrants representing at least 60%
of the shares of Common Stock obtainable upon exercise of all Warrants issued on
the Original Issuance Date then outstanding, shall retain independent public
accountants of recognized national standing selected by the Board of Directors
of the Company to make any computation required in connection with adjustments
under this Warrant, and a certificate signed by such firm absent manifest error
shall be conclusive evidence of the correctness of such adjustment, which shall
be binding on the holder and the Company.

            (ii) The Company will give written notice to the holder of this
Warrant at least ten (10) Business Days prior to the date on which the Company
closes its books or takes a record (A) with respect to any dividend or
distribution upon the Common Stock, (B) with respect to any pro rata
subscription offer to holders of Common Stock or (C) for determining rights to
vote with respect to any Organic Change (as defined below), dissolution or
liquidation, provided that the Company need not in any case provide such notice
prior to the time such information is made known to the public.

            (iii) The Company will also give written notice to the holder of
this Warrant at least ten (10) Business Days prior to the date on which any
capital reorganization of the Company, any reclassification or recapitalization
of the capital stock of the Company, any consolidation or merger involving the
Company and any other Person, any transaction or series of transactions in which
more than 50% of the voting securities of the Company are transferred to another
Person, or any transfer, sale or other disposition of all or substantially all
the assets of


                                       15
<PAGE>

the Company to any other Person (each, an "Organic Change"), dissolution or
liquidation will take place, provided that the Company need not in any case
provide such notice prior to the time such information is made known to the
public.

      h. ADJUSTMENT. No adjustment in the Warrant Exercise Price shall be
required unless such adjustment would require an increase or decrease of at
least $.01 in such price; provided, however, that any adjustments which by
reason of this sentence are not required to be made shall be carried forward and
taken into account in any subsequent adjustment required to be made hereunder.

      Section 9. LOST, STOLEN, MUTILATED OR DESTROYED WARRANT. If this Warrant
is lost, stolen, mutilated or destroyed, the Company shall promptly, on receipt
of an indemnification undertaking or other form of security reasonably
acceptable to the Company (or in the case of a mutilated Warrant, the Warrant),
issue a new Warrant of like denomination and tenor as this Warrant so lost,
stolen, mutilated or destroyed. Notwithstanding the foregoing, if this Warrant
is lost by, stolen from or destroyed by the original holder hereof, the
affidavit of such original holder setting forth the circumstances of such loss,
theft or destruction shall be accepted as satisfactory evidence thereof, and no
indemnification bond or other security shall be required by the Company as a
condition to the execution and delivery by the Company of a new Warrant to such
original holder other than such original holder's unsecured written agreement to
indemnify the Company solely for losses actually incurred by the Company as a
direct consequence of the loss, theft or destruction of the Warrant.

      Section 10. NOTICE. Any notices, consents, waivers or other communications
required or permitted to be given under the terms of this Warrant must be in
writing and will be deemed to have been delivered: (i) upon receipt, when
delivered personally; (ii) upon receipt, when sent by facsimile (provided
confirmation of transmission is mechanically or electronically generated and
kept on file by the sending party); or (iii) one (1) Business Day after deposit
with a nationally recognized overnight delivery service, in each case properly
addressed to the party to receive the same. If notice is to be sent to the
Company, the holder shall use its reasonable best efforts to provide additional
copies to the individuals listed below; provided, however, that the failure of
such holder to send such additional copies shall in no way limit the
effectiveness of any notice sent to the Company to the attention of Chief
Executive Officer as provided for below. The addresses and facsimile numbers for
such communications shall be:

                    If to the Company:

                             Hemispherx Biopharma, Inc.
                             One Penn Center
                             1617 JFK Boulevard, Suite 660
                             Philadelphia, PA  19103
                             Telephone:
                             Facsimile:
                             Attention: Chief Executive Officer


                                       16
<PAGE>

                    With a copy to:

                             Ransom W. Etheridge, Esq.
                             2610 Potters Road
                             Suite 200
                             Virginia Beach, VA  23452
                             Telephone: 757-486-0599
                             Facsimile: 757-486-0792

                  If to the Transfer Agent:

                             Continental Stock Transfer & Trust Company
                             2 Broadway
                             New York, NY 10004
                             Telephone:       (212) 509-4000
                             Facsimile:       (212) 509-5150

      If to a holder of this Warrant, to it at the address and facsimile number
set forth on the Schedule of Buyers to the Securities Purchase Agreement, with
copies to such holder's representatives as set forth on such Schedule of Buyers,
or at such other address and facsimile as shall be delivered to the Company upon
the issuance or transfer of this Warrant. Each party shall provide five days'
prior written notice to the other party of any change in address or facsimile
number. Written confirmation of receipt (A) given by the recipient of such
notice, consent, waiver or other communication, (B) mechanically or
electronically generated by the sender's facsimile machine containing the time,
date, recipient facsimile number and an image of the first page of such
transmission or (C) provided by a nationally recognized overnight delivery
service shall be rebuttable evidence of personal service, receipt by facsimile
or receipt from a nationally recognized overnight delivery service in accordance
with clause (i), (ii) or (iii) above, respectively.

      Section 11. AMENDMENTS. This Warrant and any term hereof may be amended,
changed, waived, discharged, or terminated only by an instrument in writing
signed by the party or holder hereof against which enforcement of such
amendment, change, waiver, discharge or termination is sought and shall be
binding on such party's or holder's assignees and transferees; provided,
however, that any such amendment, change, waiver, discharge or termination that
adversely impacts the holders of any of the Warrants other than this Warrant may
be made only if the Company has obtained the written consent of the holders of
Warrants representing at least 60% of the shares of Common Stock issuable upon
exercise of all of the Warrants issued on the Original Issuance Date then
outstanding; provided, further, that no such action may increase the Warrant
Exercise Price or decrease the number of shares or class of stock issuable upon
exercise of any Warrants without the written consent of the holder of such
Warrant. No waivers of any term, condition or provision of this Warrant in any
one or more instances shall be deemed to be or construed as a further or
continuing waiver of any such term, condition or provision.

      Section 12. DATE. The date of this Warrant is March 12, 2003 (the "Warrant
Date"). This Warrant, in all events, shall be wholly void and of no effect after
the close of


                                       17
<PAGE>

business on the Expiration Date, except that notwithstanding any other
provisions hereof, the provisions of Section 7(c) shall continue in full force
and effect after such date as to any Warrant Shares or other securities issued
upon the exercise of this Warrant.

      Section 13. LIMITATION ON NUMBER OF WARRANT SHARES. The Company shall not
be obligated to issue Warrant Shares upon exercise of this Warrant to the extent
that the issuance of such shares of Common Stock would cause the Company to
exceed that number of shares of Common Stock which the Company may issue upon
exercise of this Warrant (the "Exchange Cap") without breaching the Company's
obligations under the rules or regulations of the Principal Market, except that
such limitation shall not apply in the event that the Company obtains the
approval of its stockholders as required by the Principal Market (or any
successor rule or regulation) for issuances of Common Stock in excess of such
amount. Until such approval is obtained, the holder of this Warrant shall not be
issued, upon exercise of this Warrant, Warrant Shares in an amount, which if
added to the aggregate number of Defeasance Shares, Interest Shares and
Conversion Shares issued to the holder of this Warrant (and all predecessor
holders) under the Convertible Debentures held by the holder (and all
predecessor holders) as of the date of such exercise would exceed such holder's
Cap Allocation Amount (as such term is defined in the Convertible Debenture). If
at any time when the holder delivers an Exercise Notice pursuant to Section 2
hereof the Company shall be prohibited pursuant to the provisions of this
Section 13 from issuing any Warrant Shares, then the Company shall pay in
immediately available funds to the holder of this Warrant within two (2)
Business Days of the date of delivery of such Exercise Notice, an amount in cash
equal to the product of (X) the number of shares of Common Stock which could not
be issued by virtue of the limitations contained in this Section 13 multiplied
by (Y) the excess of (1) the average of the Closing Sale Prices of the Common
Stock on each of the five (5) trading days ending on the third trading day
immediately preceding the date such prohibition arises over (2) the Warrant
Exercise Price then in effect. The number of shares issuable upon exercise of
this Warrant shall be reduced for each share for which the Company makes a cash
payment pursuant to the preceding sentence.

      Section 14. Judicial Proceedings. Any legal action, suit or proceeding
brought against the Company with respect to this Warrant may be brought in any
federal court of the Southern District of New York or any state court located in
New York County, State of New York, and by execution and delivery of this
Warrant, the Company hereby irrevocably and unconditionally waives any claim (by
way of motion, as a defense or otherwise) of improper venue, that it is not
subject personally to the jurisdiction of such court, that such courts are an
inconvenient forum or that this Warrant or the subject matter may not be
enforced in or by such court. The Company hereby irrevocably and unconditionally
consents to the service of process of any of the aforementioned courts in any
such action, suit or proceeding by the mailing of copies thereof by registered
or certified mail, postage prepaid, at its address set forth or provided for in
Section 10, such service to become effective 10 days after such mailing. Nothing
herein contained shall be deemed to affect the right of any party to serve
process in any manner permitted by law or commence legal proceedings or
otherwise proceed against any other party in any other jurisdiction to enforce
judgments obtained in any action, suit or proceeding brought pursuant to this
Section. The Company irrevocably submits to the exclusive jurisdiction of the
aforementioned courts in such action, suit or proceeding


                                       18
<PAGE>

      Section 15. DESCRIPTIVE HEADINGS; GOVERNING LAW. The descriptive headings
of the several sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant. The corporate
laws of the State of New York shall govern all issues concerning the relative
rights of the Company and its stockholders. All other questions concerning the
construction, validity, enforcement and interpretation of this Warrant shall be
governed by the internal laws of the State of New York, without giving effect to
any choice of law or conflict of law provision or rule (whether of the State of
New York or any other jurisdiction) that would cause the application of the laws
of any jurisdiction other than the State of New York.

                                    [* * * *]


                                       19
<PAGE>

      IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by as
of the 12th day of March, 2003.

                               HEMISPHERX BIOPHARMA, INC.





                               By:
                                          -------------------------------
                               Name:
                                          -------------------------------
                               Title:
                                          -------------------------------


                                       20
<PAGE>

                              EXHIBIT A TO WARRANT

                                 EXERCISE NOTICE
        TO BE EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS WARRANT
                           HEMISPHERX BIOPHARMA, INC.

The undersigned holder hereby exercises the right to purchase ______________ of
the shares of Common Stock ("Warrant Shares") of HEMISPHERX BIOPHARMA, INC., a
Delaware corporation (the "Company"), evidenced by the attached Warrant (the
"Warrant"). Capitalized terms used herein and not otherwise defined shall have
the respective meanings set forth in the Warrant.

      1. Form of Warrant Exercise Price. The Holder intends that payment of the
Warrant Exercise Price shall be made as:

      ______   "Cash Exercise" with respect to ________ Warrant Shares; and/or

      ______   "Cashless   Exercise"  with  respect  to
               ______  Warrant  Shares  (to the  extent
               permitted by the terms of the Warrant).

      2. Variable Price. Is the Variable Price being relied on pursuant to
Section 8(c) of the Warrant? (check one) YES ____ No ____

      3. Payment of Warrant Exercise Price. In the event that the holder has
elected a Cash Exercise with respect to some or all of the Warrant Shares to be
issued pursuant hereto, the holder shall pay the sum of $___________________ to
the Company in accordance with the terms of the Warrant.

      4. Delivery of Warrant Shares. The holder of this warrant has sold or will
sell the shares of common stock issuable pursuant to this Notice pursuant to a
registration statement or an exemption from registration under the Securities
Act of 1933, as amended.

      5. Private Placement Representations. The holder of this Warrant confirms
the continuing validity of, and reaffirms as of the date hereof, its
representations and warranties set forth in Section 6 of the Warrant.

Date:
      --------------- --, ----

---------------------------------------         --------------------------------
Name of Registered Holder                         Tax ID of Registered Holder
                                                         (if applicable)

By:
   ---------------------------------

Name:
     -------------------------------

Title:
      ------------------------------


                                       21
<PAGE>

                                 ACKNOWLEDGMENT

      The Company hereby acknowledges this Exercise Notice and hereby directs
Continental Stock Transfer & Trust Company to issue the above indicated number
of shares of Common Stock in accordance with the Irrevocable Transfer Agent
Instructions dated March 12, 2003 from the Company and acknowledged and agreed
to by Continental Stock Transfer & Trust Company.

                              HEMISPHERX BIOPHARMA, INC.

                              By:
                                 -------------------------------
                                     Name:
                                     Title:


                                       22
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                              EXHIBIT B TO WARRANT

                                 FORM OF WARRANT

      FOR VALUE RECEIVED, the undersigned does hereby assign and transfer to
________________, Federal Identification No. __________, a warrant to purchase
____________ shares of the capital stock of HEMISPHERX BIOPHARM, INC., a
Delaware corporation, represented by warrant certificate no. _____, standing in
the name of the undersigned on the books of said corporation. The undersigned
does hereby irrevocably constitute and appoint ______________, attorney to
transfer the warrants of said corporation, with full power of substitution in
the premises.

Dated:  _________, 200_



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                                         Its:
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