<PAGE>

                                                                     EXHIBIT 4.5

NEITHER THIS WARRANT NOR ANY OF THE SHARES OF CAPITAL STOCK ISSUED UPON ANY
EXERCISE HEREOF HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY APPLICABLE STATE SECURITIES LAWS, AND NONE OF SUCH SECURITIES
MAY BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A
REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THIS WARRANT OR SUCH SHARES, AS
APPLICABLE, UNDER SUCH ACT AND APPLICABLE LAWS OR SOME OTHER EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE LAWS OR AN OPINION OF
COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

                                      Warrant to Purchase Shares of Common Stock

                        WARRANT TO PURCHASE COMMON STOCK
                                       OF
                             XENONICS HOLDINGS, INC.

      This certifies that, for value received, Texrock, Ltd. (the "Holder"), or
registered assigns, is entitled, subject to the terms set forth below, to
purchase from Xenonics Holdings, Inc., a Nevada corporation (the "Company"),
shares of the Company's $0.001 par value common stock (the "Common Stock"), upon
surrender hereof, at the principal office of the Company, with the subscription
form attached hereto duly executed, and simultaneous payment therefor in lawful
money of the United States, at the Exercise Price as set forth in Section 2
below. The Exercise Price of such shares of Common Stock is subject to
adjustment as provided in Section 2 and Section 11 of this Warrant. The term
"Warrant" as used herein shall include this Warrant, and any warrants delivered
in substitution or exchange therefor.

      1.    Term of Warrant. Subject to the terms and conditions set forth
herein, this Warrant shall be exercisable, in whole or in part, during the term
commencing on April 26, 2003 and ending April 25, 2008.

      2.    Number of Shares of Common Stock; Exercise Price.

            (a)   During the term of this Warrant, this Warrant may be exercised
for the purchase of shares of Common Stock.

            (b)   The number of shares of Common Stock that can be purchased
upon the exercise of this Warrant shall be ten thousand (10,000) (as
appropriately adjusted for any anti-dilution rights, stock dividends, splits or
similar events).

            (c)   The Exercise Price at which this Warrant may be exercised
shall be $8.00 per share (as appropriately adjusted for any anti-dilution
rights, stock dividends, splits or similar events).

<PAGE>

      3.    Exercise of Warrant.

            (a)   The purchase rights represented by this Warrant are
exercisable by the Holder in whole or in part, but not for less than one
thousand (1,000) shares at a time (or such lesser number of shares which may
then constitute the maximum number purchasable; such number being subject to
adjustment as provided in Section 11 below), at any time, or from time to time,
during the term hereof as described in Section 1 above, by the surrender of this
Warrant and the Notice of Exercise annexed hereto duly completed and executed on
behalf of the Holder, at the office of the Company (or such other office or
agency of the Company as it may designate by notice in writing to the Holder at
the address of the Holder appearing on the books of the Company), upon payment
in cash or by check acceptable to the Company of the purchase price of the
shares of Common Stock to be purchased.

      This Warrant shall be deemed to have been exercised immediately prior to
the close of business on the date of its surrender for exercise as provided
above, and the person entitled to receive the shares of Common Stock issuable
upon such exercise shall be treated for all purposes as the holder of record of
such shares as of the close of business on such date. As promptly as practicable
on or after such date and in any event within ten (10) days thereafter, the
Company at its expense shall issue and deliver to the person or persons entitled
to receive the same a certificate or certificates for the number of shares
issuable upon such exercise. In the event that this Warrant is exercised in
part, the Company at its expense will execute and deliver a new Warrant of like
tenor exercisable for the number of shares for which this Warrant may then be
exercised.

      4.    No Fractional Shares or Scrip. No fractional shares or scrip
representing fractional shares shall be issued upon the exercise of this
Warrant. In lieu of any fractional share to which the Holder would otherwise be
entitled, the Company shall make a cash payment equal to the Exercise Price then
in effect multiplied by such fraction.

      5.    Replacement of Warrant. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and substance to the Company
or, in the case of mutilation, on surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor and amount.

      6.    Rights of Stockholders. The Holder 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, as such, any of the rights of a stockholder of the
Company or any right to vote for the election of directors or upon any matter
submitted to stockholders 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 this
Warrant shall have been exercised as provided herein.

                                       2
<PAGE>

      7.    Transfer of Warrant.

            (a)   Warrant Register. The Company will maintain a register (the
"Warrant Register") containing the names and addresses of the Holder or Holders.
Any Holder of this Warrant or any portion hereof may change its address as shown
on the Warrant Register by written notice to the Company requesting such change.
Any notice or written communication required or permitted to be given to the
Holder may be delivered or given by mail to such Holder as shown on the Warrant
Register and at the address shown on the Warrant Register. Until this Warrant is
transferred on the Warrant Register of the Company, the Company may treat the
Holder as shown on the Warrant Register as the absolute owner of this Warrant
for all purposes, notwithstanding any notice to the contrary.

            (b)   Warrant Agent. The Company may, by written notice to the
Holder, appoint an agent for the purpose of maintaining the Warrant Register
referred to in Section 7(a) above, issuing the Common Stock or other securities
then issuable upon the exercise of this Warrant, exchanging this Warrant,
replacing this Warrant, or any or all of the foregoing. Thereafter, any such
registration, issuance, exchange, or replacement, as the case may be, shall be
made at the office of such agent.

            (c)   Transferability and Nonnegotiability of Warrant. This Warrant
may not be transferred or assigned in whole or in part without compliance with
all applicable federal and state securities laws by the transferor and the
transferee (including the delivery of investment representation letters and
legal opinions reasonably satisfactory to the Company, if such are requested by
the Company). Subject to the provisions of this Warrant with respect to
compliance with the Securities Act of 1933, as amended (the "Act"), title to
this Warrant may be transferred by endorsement (by the Holder executing the
Assignment Form annexed hereto) and delivery in the same manner as a negotiable
instrument transferable by endorsement and delivery.

            (d)   Exchange of Warrant Upon a Transfer. On surrender of this
Warrant for exchange, properly endorsed on the Assignment Form and subject to
the provisions of this Warrant with respect to compliance with the Act, the
Company at its expense shall issue to or on the order of the Holder a new
warrant or warrants of like tenor, in the name of the Holder or as the Holder
(on payment by the Holder of any applicable transfer taxes) may direct, for the
number of shares issuable upon exercise hereof. In the event of a partial
transfer by a Holder, the Company shall issue to the holders one or more
appropriate new warrants.

            (e)   Compliance with Securities Laws. All shares of Common Stock
issued upon exercise hereof shall be stamped or imprinted with a legend in
substantially the following form (in addition to any legend required by state
securities laws):

THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT AND
NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF, AND
HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. SUCH
SHARES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR
UNLESS THE SALE OR TRANSFER IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS
DELIVERY REQUIREMENTS OF SAID ACT.

                                       3
<PAGE>

      8.    Reservation of Stock. The Company covenants that during the term
this Warrant is exercisable, the Company will reserve from its authorized and
unissued Common Stock a sufficient number of shares to provide for the issuance
of Common Stock upon the exercise of this Warrant and, from time to time, will
take all steps necessary to amend its charter documents to provide sufficient
reserves of shares of Common Stock issuable upon exercise of this Warrant. The
Company further covenants that all shares that may be issued upon the exercise
of rights represented by this Warrant and payment of the Exercise Price, all as
set forth herein, will be free from all taxes, liens and charges in respect of
the issue thereof (other than taxes in respect of any transfer occurring
contemporaneously or otherwise specified herein). The Company agrees that its
issuance of this Warrant shall constitute full authority to its officers who are
charged with the duty of executing stock certificates to execute and issue the
necessary certificates for shares of Common Stock upon the exercise of this
Warrant. The Company covenants that all such shares of Common Stock will, when
issued, be duly and validly issued, fully paid and nonassessable.

      9.    Notices.

            (a)   Whenever the Exercise Price or number of shares purchasable
hereunder shall be adjusted pursuant to Section 11 hereof, the Company shall
issue a certificate signed by a duly authorized officer setting forth, in
reasonable detail, the event requiring the adjustment, the amount of the
adjustment, the method by which such adjustment was calculated, and the Exercise
Price and number of shares purchasable hereunder after giving effect to such
adjustment, and shall cause a copy of such certificate to be mailed (by
first-class mail, postage prepaid) to the Holder of this Warrant.

            (b)   In case:

                  (i)   the Company shall take a record of the holders of its
Common Stock (or other stock or securities at the time receivable upon the
exercise of this Warrant) for the purpose of entitling them to receive any
dividend or other distribution, or any right to subscribe for or purchase any
shares of stock of any class or any other securities, or to receive any other
right, or

                  (ii)  of any capital reorganization of the Company, any
reclassification of the capital stock of the Company, any consolidation or
merger of the Company with or into another corporation, or any conveyance of all
or substantially all of the assets of the Company to another corporation, or

                  (iii) of any voluntary dissolution, liquidation or winding-up
of the Company,

then, and in each such case, the Company will mail or cause to be mailed to the
Holder or Holders a notice specifying, as the case may be, (A) the date on which
a record is to be taken for the purpose of such dividend, distribution or right,
and stating the amount and character of such dividend, distribution or right, or
(B) the date on which such reorganization, reclassification, consolidation,
merger, conveyance, dissolution, liquidation or winding-up is to take place, and
the time, if any is to be fixed, as of which the holders of record of Common
Stock (or such stock or securities at the time receivable upon the exercise of
this Warrant) shall be entitled to

                                       4
<PAGE>

exchange their shares of Common Stock (or such other stock or securities) for
securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, conveyance, dissolution, liquidation or
winding-up. Such notice shall be mailed at least 15 days prior to the date
therein specified.

            (c)   All such notices, advices and communications shall be deemed
to have been received (i) in the case of personal delivery, on the date of such
delivery and (ii) in the case of mailing, on the first business day following
the date of such mailing.

      10.   Waivers and Amendments.

            (a)   Any term of this Warrant may be amended or waived only with
the written consent of the Company and the Holder.

            (b)   No waivers of, or exceptions to, 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.

      11.   Adjustments. The Exercise Price and the number of shares purchasable
hereunder are subject to adjustment from time to time as follows:

            (a)   Merger, Sale of Assets, etc. If at any time while this
Warrant, or any portion hereof, is outstanding and unexpired there shall be (i)
a reorganization (other than a combination, reclassification, exchange or
subdivision of shares otherwise provided for herein), (ii) a merger or
consolidation of the Company with or into another corporation in which the
Company is not the surviving entity, or a reverse triangular merger in which the
Company is the surviving entity but the shares of the Company's capital stock
outstanding immediately prior to the merger are converted by virtue of the
merger into other property, whether in the form of securities, cash, or
otherwise, or (iii) a sale or transfer of the Company's properties and assets
as, or substantially as, an entirety to any other person, then, as a part of
such reorganization, merger, consolidation, sale or transfer, lawful provision
shall be made so that the holder of this Warrant shall thereafter be entitled to
receive upon exercise of this Warrant, during the period specified herein and
upon payment of the Exercise Price then in effect, the number of shares of stock
or other securities or property of the successor corporation resulting from such
reorganization, merger, consolidation, sale or transfer that a holder of the
shares deliverable upon exercise of this Warrant would have been entitled to
receive in such reorganization, consolidation, merger, sale or transfer if this
Warrant had been exercised immediately before such reorganization, merger,
consolidation, sale or transfer, all subject to further adjustment as provided
in this Section 11. The foregoing provisions of this Section 11 shall similarly
apply to successive reorganizations, consolidations, mergers, sales and
transfers and to the stock or securities of any other corporation that are at
the time receivable upon the exercise of this Warrant. If the per share
consideration payable to the Holder hereof for shares in connection with any
such transaction is in a form other than cash or marketable securities, then the
value of such consideration shall be determined in good faith by the Company's
Board of Directors. In all events, appropriate adjustment (as determined in good
faith by the Company's Board of Directors) shall be made in the application of
the provisions of this Warrant with respect to the rights and interests of the
Holder after the transaction, to the end that the provisions of this Warrant
shall be applicable after that event, as

                                       5
<PAGE>

near as reasonably may be, in relation to any shares or other property
deliverable after that event upon exercise of this Warrant.

            (b)   Reclassification, etc. If the Company, at any time while this
Warrant, or any portion hereof, remains outstanding and unexpired by
reclassification of securities or otherwise, shall change any of the securities
as to which purchase rights under this Warrant exist into the same or a
different number of securities of any other class or classes, this Warrant shall
thereafter represent the right to acquire such number and kind of securities as
would have been issuable as the result of such change with respect to the
securities that were subject to the purchase rights under this Warrant
immediately prior to such reclassification or other change and the Exercise
Price therefor shall be appropriately adjusted, all subject to further
adjustment as provided in this Section 11.

            (c)   Split, Subdivision or Combination of Shares. If the Company at
any time while this Warrant, or any portion hereof, remains outstanding and
unexpired shall split, subdivide or combine the securities as to which purchase
rights under this Warrant exist, into a different number of securities of the
same class, then (i) the Exercise Price for such securities shall be
proportionately decreased in the case of a split or subdivision or
proportionately increased in the case of a combination, and (ii) the number of
shares issuable hereunder shall be proportionately increased or decreased, as
the case may be, in both cases according to the ratio which the total number of
shares of such security to be outstanding immediately after such event bears to
the total number of shares of such security outstanding immediately prior to
such event.

            (d)   Adjustments for Dividends in Stock or Other Securities or
Property. If while this Warrant, or any portion hereof, remains outstanding and
unexpired, the holders of the securities as to which purchase rights under this
Warrant exist at the time shall have received, or, on or after the record date
fixed for the determination of eligible stockholders, shall have become entitled
to receive, without payment therefor, other or additional stock or other
securities or property (other than cash) of the Company by way of dividend, then
and in each case, this Warrant shall represent the right to acquire, in addition
to the number of shares of the security receivable upon exercise of this
Warrant, and without payment of any additional consideration therefor, the
amount of such other or additional stock or other securities or property (other
than cash) of the Company that such holder would hold on the date of such
exercise had it been the holder of record of the security receivable upon
exercise of this Warrant on the date hereof and had thereafter, during the
period from the date hereof to and including the date of such exercise, retained
such shares and/or all other additional stock available by it as aforesaid
during such period, giving effect to all adjustments called for during such
period by the provisions of this Section 11.

            (e)   Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment pursuant to this Section 11, the Company at its
expense shall promptly compute such adjustment or readjustment in accordance
with the terms hereof and furnish to each Holder of this Warrant a certificate
setting forth such adjustment or readjustment and showing in detail the facts
upon which such adjustment or readjustment is based.

            (f)   No Impairment. The Company will not, by amendment of its
charter documents or through any reorganization, transfer of assets,
consolidation, merger, dissolution,

                                       6
<PAGE>

or any other similar voluntary action, avoid or seek to avoid the observance or
performance of any of the terms of this Warrant, but will at times in good faith
assist in the carrying out of all such terms and in the taking of all such
action as may be necessary or appropriate in order to protect the rights of the
holder of this Warrant against impairment due to such event. Without limiting
the generality of the foregoing, the Company (a) will take all action that may
be necessary or appropriate in order that the Company may validly and legally
issue fully paid and nonassessable shares of stock, free from all taxes, liens
and charges with respect to the issue thereof, on the exercise of all of the
Warrants from time to time outstanding, and (b) will not consolidate with or
merge into any other person or permit any such person to consolidate with or
merge into the Company (if the Company is not the surviving person), unless such
other person shall expressly assume in writing and agree to be bound by all the
terms of this Warrant.

      12.   Descriptive Headings and Governing Law. The description headings of
the several sections and paragraphs of this Warrant are inserted for convenience
only and do not constitute a part of this Warrant. This Warrant shall be
construed and enforced in accordance with, and the rights of the parties shall
be governed by, the laws of the State of California without regard to conflicts
of law provisions.

      13.   Speculative Value of Warrant. It is understood and agreed by the
Company and Holder that the Warrant as of the date of issuance has a speculative
value and no definitive value can be expressed.

      14.   Notices. All notices and other communications hereunder shall be
delivered by hand, by depositing the notice in the United States mail postage
prepaid and properly addressed to the recipient or by facsimile transmission to
the parties as follow:

            (a) If to the Company:       Xenonics Holdings, Inc.
                                         2236 Rutherford Road, Suite 123
                                         Carlsbad, California 92008
                                         Telephone: (760) 438-4004
                                         Fax: (760) 438-1184

            (b) If to the Holder:        c/o White Rock Capital Partners, L.P.
                                         3131 Turtle Creek Blvd., Suite 800
                                         Dallas, Texas, 75219

                                       7
<PAGE>

      IN WITNESS WHEREOF, XENONICS HOLDINGS, INC. has caused this Warrant to be
executed by its officer thereunto duly authorized.

Dated: April 26, 2004

                                         XENONICS HOLDINGS, INC.

                                         By:____________________________________
                                            Name:
                                            Title:

                                        8
<PAGE>

                               NOTICE OF EXERCISE

To:   XENONICS HOLDINGS, INC.

      (1)   The undersigned hereby elects to purchase [_________] shares of
Common Stock of XENONICS HOLDINGS, INC., pursuant to the provisions of the
attached Warrant, and tenders herewith payment of the purchase price for such
shares in full.

      (2)   In exercising this Warrant, the undersigned hereby confirms and
acknowledges that the shares of Common Stock to be issued are being acquired
solely for the account of the undersigned and not as a nominee for any other
party, and for investment, and that the undersigned will not offer, sell or
otherwise dispose of any such shares of Common Stock except under circumstances
that will not result in a violation of the Securities Act of 1933, as amended,
or any applicable state securities laws.

      (3)   Please issue a certificate or certificates representing said shares
of Common Stock in the name of the undersigned or in such other name as is
specified below:

                                         _______________________________________
                                                        (Name)

      (4)   Please issue a new Warrant for the unexercised portion of the
attached Warrant in the name of the undersigned or in such other name as is
specified below:

____________________________________
Name:
Date:

                                        9
<PAGE>

                                 ASSIGNMENT FORM

      FOR VALUE RECEIVED, the undersigned registered owner of this Warrant
hereby sells, assigns and transfers unto the Assignee named below all of the
rights of the undersigned under the within Warrant, with respect to the number
of shares of Common Stock set forth below:

  NAME OF ASSIGNEE                 ADDRESS                 NO. OF SHARES

__________________  _________________________________  ______________________
                    _________________________________
                    _________________________________

and does hereby irrevocably constitute and appoint _____________ Attorney to
make such transfer on the books of the XENONICS HOLDINGS, INC., maintained for
the purpose, with full power of substitution in the premises.

      The undersigned also represents that, by assignment hereof, the Assignee
acknowledges that this Warrant and the shares of stock to be issued upon
exercise hereof are being acquired for investment and that the Assignee will not
offer, sell or otherwise dispose of this Warrant or any shares of 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, or any state securities
laws. Further, the Assignee has acknowledged that upon exercise of this Warrant,
the Assignee shall, if requested by the Company, confirm in writing, in a form
reasonably satisfactory to the Company, that the shares of stock so purchased
are being acquired for investment and not with a view toward distribution or
resale.

Name:_________________________________
Dated:________________________________

                                       10