AMENDED AND RESTATED SECURITIES PURCHASE AGREEMENT


           THIS AMENDED AND RESTATED SECURITIES PURCHASE AGREEMENT,  dated as of
the date of acceptance set forth below, is entered into by and between XYBERNAUT
CORPORATION,  a Delaware  corporation,  with headquarters  located at 12701 Fair
Lakes Circle,  Fairfax,  Virginia 22033  ("Company"),  and the undersigned  (the
"Buyer").

                              W I T N E S S E T H:

           WHEREAS,  the  Company  and the Buyer,  in order to amend and restate
that  certain  Securities  Purchase  Agreement  to which they are  parties,  are
executing and delivering  this Agreement in accordance with and in reliance upon
the exemption from  securities  registration  afforded,  inter alia, by Rule 506
under  Regulation  D  ("Regulation  D")  as  promulgated  by the  United  States
Securities and Exchange Commission (the "SEC") under the Securities Act of 1933,
as amended (the "1933 Act"), and/or Section 4(2) of the 1933 Act; and

           WHEREAS, the Buyer wishes to purchase,  upon the terms and subject to
the conditions of this Agreement, 4% Convertible Preferred Stock, $.01 par value
per share (the  "Convertible  Preferred  Stock"),  of the Company  which will be
convertible into shares of Common Stock, $.01 par value per share of the Company
(the  "Common  Stock"),  upon the terms and  subject  to the  conditions  of the
Convertible  Preferred Stock, and subject to acceptance of this Agreement by the
Company;

           NOW  THEREFORE,  in  consideration  of the  premises  and the  mutual
covenants  contained  herein  and other  good and  valuable  consideration,  the
receipt and sufficiency of which are hereby  acknowledged,  the parties agree as
follows:

           1. AGREEMENT TO PURCHASE; PURCHASE PRICE.

           a. Purchase.  (i) The undersigned  hereby agrees to purchase from the
Company shares of the  Convertible  Preferred  Stock in the amounts set forth on
the signature page of this Agreement on the Closing Date (as defined below) (the
"Initial  Preferred  Stock"),  and on the  Additional  Closing  Date (as defined
below) (the "Additional Preferred Stock"), out of a total offering of $4,000,000
of such  Preferred  Stock,  and having the terms and conditions set forth in the
certificate of designation to the  Certificate of  Incorporation  of the Company
attached  hereto as Annex I (the  "Certificate  of  Designation").  The purchase
price for the Initial  Preferred Stock and the Additional  Preferred Stock shall
be as set forth on the  signature  page  hereto  and shall be  payable in United
States Dollars.


                                        1





           (ii) As used  herein,  the term  "Preferred  Stock" means the Initial
Preferred Stock and the Additional Preferred Stock, unless the context otherwise
requires.

           (iii) As used  herein,  the term  "Securities"  means  the  Preferred
Stock.

           b. Form of Payment.  The Buyer shall pay the  purchase  price for the
Initial  Preferred Stock or the Additional  Preferred Stock, as the case may be,
by delivering  immediately  available good funds in United States Dollars to the
escrow agent (the "Escrow  Agent")  identified in the Joint Escrow  Instructions
attached  hereto  as  Annex  II  (the  "Joint  Escrow  Instructions").  Promptly
following  payment by the Buyer to the Escrow Agent of the purchase price of the
relevant  Preferred Stock, the Company shall deliver a certificate  representing
the  relevant  Preferred  Stock duly  executed  on behalf of the  Company to the
Escrow Agent. By signing this Agreement,  the Buyer and the Company, and subject
to  acceptance  by the  Escrow  Agent,  each  agrees  to all  of the  terms  and
conditions of, and becomes a party to, the Joint Escrow Instructions, all of the
provisions of which are incorporated herein by this reference as if set forth in
full.

           c. Method of Payment.  Payment into escrow of the purchase  price for
the relevant Preferred Stock shall be made by wire transfer of funds to:

                         Bank of New York
                         350 Fifth Avenue
                         New York, New York 10001

                         ABA# 021000018
                         For credit to the account of Krieger & Prager, Esqs.
                         Account No.:  637-1657450

Not later than 1:00 p.m.,  New York time,  on the date which is one (1) New York
Stock Exchange trading days after the Company shall have accepted this Agreement
and  returned a signed  counterpart  of this  Agreement  to the Escrow  Agent by
facsimile,  the Buyer shall deposit with the Escrow Agent the aggregate purchase
price for the Initial Preferred Stock, in currently  available funds. Time is of
the essence with respect to such payment,  and failure by the Buyer to make such
payment, shall allow the Company to cancel this Agreement.

           d.  Escrow  Property.  The  purchase  price  and  the  certificate(s)
representing  the Preferred  Stock delivered to the Escrow Agent as contemplated
by Sections 1(b) and (c) hereof are referred to as the "Escrow Property."


                                        2





           2. BUYER  REPRESENTATIONS,  WARRANTIES,  ETC.; ACCESS TO INFORMATION;
INDEPENDENT INVESTIGATION.

           The Buyer  represents and warrants to, and covenants and agrees with,
the Company as follows:

           a. Without  limiting  Buyer's right to sell the Common Stock pursuant
to the  Registration  Statement  (as that term is  defined  in the  Registration
Rights Agreement defined below), the Buyer is purchasing the Preferred Stock and
will be acquiring  the shares of Common Stock  issuable  upon  conversion of the
Preferred Stock (the "Converted Shares") for its own account for investment only
and not with a view towards the public sale or distribution thereof and not with
a view to or for sale in connection with any distribution thereof;

           b. The Buyer is (i) an "accredited  investor" as that term is defined
in Rule 501 of the General Rules and Regulations under the 1933 Act by reason of
Rule 501(a)(3),  (ii) experienced in making investments of the kind described in
this Agreement and the related documents,  (iii) able, by reason of the business
and  financial  experience  of its  officers  (if an  entity)  and  professional
advisors (who are not  affiliated  with or compensated in any way by the Company
or any of its  affiliates  or selling  agents),  to protect its own interests in
connection with the  transactions  described in this Agreement,  and the related
documents,  and (iv) able to afford the  entire  loss of its  investment  in the
Securities;

           c. All  subsequent  offers and sales of the  Preferred  Stock and the
shares of Common  Stock  representing  the  Converted  Shares (such Common Stock
sometimes  referred to as the  "Shares") by the Buyer shall be made  pursuant to
registration  of the Shares under the 1933 Act or pursuant to an exemption  from
registration;

           d. The Buyer  understands  that the Preferred  Stock is being offered
and  sold  to it in  reliance  on  specific  exemptions  from  the  registration
requirements  of United States  federal and state  securities  laws and that the
Company is relying upon the truth and  accuracy  of, and the Buyer's  compliance
with,  the   representations,   warranties,   agreements,   acknowledgments  and
understandings  of the  Buyer  set  forth  herein  in  order  to  determine  the
availability  of such exemptions and the eligibility of the Buyer to acquire the
Preferred Stock and to receive the Shares upon conversion;

           e. The Buyer and its advisors,  if any, have been  furnished with all
materials  relating to the business,  finances and operations of the Company and
materials relating to the offer and sale of the Preferred Stock and the offer of
the Shares which have been requested by the Buyer, including Annex V hereto. The
Buyer and its  advisors,  if any,  have been  afforded  the  opportunity  to ask
questions of the Company and have received complete and satisfactory  answers to
any such inquiries.  Without limiting the generality of the foregoing, the Buyer
has also had the opportunity


                                        3





to obtain and to review  the  Company's  (1) Annual  Report on Form 10-K for the
fiscal year ended December 31, 1997, (2) Quarterly  Reports on Form 10-Q for the
fiscal  quarters  ended June 30, 1997 and March 31,  1997,  (3) Forms 8-K dated,
June 30, 1997, and (4) Form S-3 filed on September 22, 1997 (the  "Company's SEC
Documents").

           f. The  Buyer  understands  that  its  investment  in the  Securities
involves a high degree of risk;

           g. The Buyer  understands  that no  United  States  federal  or state
agency or any other government or governmental  agency has passed on or made any
recommendation or endorsement of the Securities;

           h. This Agreement has been duly and validly authorized,  executed and
delivered  on behalf of the Buyer and is a valid and  binding  agreement  of the
Buyer enforceable in accordance with its terms,  subject as to enforceability to
general principles of equity and to bankruptcy, insolvency, moratorium and other
similar laws affecting the enforcement of creditors' rights generally.

           i. Neither the Buyer,  nor any  affiliate of the Buyer nor any person
acting on its or their  behalf,  has any  intention  of entering  into,  any put
option,  short position or other similar  instrument or position with respect to
the  Preferred  Stock  or the  Shares,  and  neither  the  Buyer  nor any of its
affiliates  nor any person  acting on its or their  behalf  will at any time use
Shares  acquired upon  conversion of the Preferred  Stock to settle or cover any
put option, short position or other similar instrument or position.

           j.  Notwithstanding  the provisions hereof or of the Preferred Stock,
in no event  (except with respect to an automatic  conversion  of the  Preferred
Stock as  provided  in the  Certificate  of  Designations)  shall the  holder be
entitled  to  convert  any  Preferred  Stock  to the  extent  that,  after  such
conversion,  the sum of (1) the  number of shares of Common  Stock  beneficially
owned by the Buyer and its  affiliates  (other than shares of Common Stock which
may be deemed  beneficially  owned  through  the  ownership  of the  unconverted
portion of the  Preferred  Stock),  and (2) the number of shares of Common Stock
issuable upon the  conversion  of the Preferred  Stock with respect to which the
determination  of this  proviso  is  being  made,  would  result  in  beneficial
ownership by the Buyer and its affiliates of more than 4.99% of the  outstanding
shares of Common Stock. For purposes of the proviso to the immediately preceding
sentence,  beneficial  ownership  shall be determined in accordance with Section
13(d) of the  Securities  Exchange  Act of 1934,  as amended  (the "1934  Act"),
except as otherwise provided in clause (1) of such proviso.

           3. COMPANY REPRESENTATIONS, ETC.

           The Company represents and warrants to the Buyer that:



                                        4





           a. Concerning the Preferred Stock and the Shares. The Preferred Stock
has been duly  authorized,  and when  issued,  will be duly and validly  issued,
fully  paid and  non-assessable  and will not  subject  the  holder  thereof  to
personal  liability  by reason of being  such  holder.  There are no  preemptive
rights of any  stockholder  of the Company,  as such,  to acquire the  Preferred
Stock or the Converted Shares.

           b.  Reporting  Company  Status.  The  Company is a  corporation  duly
organized,  validly existing and in good standing under the laws of the State of
Delaware and has the  requisite  corporate  power to own its  properties  and to
carry on its business as now being conducted. The Company is duly qualified as a
foreign  corporation to do business and is in good standing in each jurisdiction
where the nature of the business  conducted  or property  owned by it makes such
qualification necessary,  other than those jurisdictions in which the failure to
so qualify would not have a material adverse effect on the business,  operations
or condition (financial or otherwise) of the Company. The Company has registered
its Common Stock pursuant to Section 12 of the Securities  Exchange Act of 1934,
as amended (the  "Exchange  Act"),  and the Common Stock is listed and traded on
The NASDAQ/SmallCap  Market. The Company has received no notice,  either oral or
written,  with respect to the continued eligibility of the Common Stock for such
listing, and the Company has maintained all requirements for the continuation of
such listing.

           c.  Authorized  Shares.  The Company has  sufficient  authorized  and
unissued  Shares as may be reasonably  necessary to effect the conversion of the
Preferred Stock. The Converted Shares have been duly authorized and, when issued
upon  conversion  of, or as interest on, the Preferred  Stock,  will be duly and
validly issued,  fully paid and  non-assessable  and will not subject the holder
thereof to personal liability by reason of being such holder.

           d. Securities Purchase  Agreement;  Registration Rights Agreement and
Stock. This Agreement and the Registration  Rights Agreement,  the form of which
is attached hereto as Annex IV (the "Registration  Rights  Agreement"),  and the
transactions  contemplated thereby, have been duly and validly authorized by the
Company,  this Agreement has been duly executed and delivered by the Company and
this  Agreement is, and the  Registration  Rights  Agreement,  when executed and
delivered by the Company,  will be, valid and binding  agreements of the Company
enforceable  in  accordance  with  their   respective   terms,   subject  as  to
enforceability  to general  principles of equity and to bankruptcy,  insolvency,
moratorium,  and other  similar laws  affecting  the  enforcement  of creditors'
rights  generally;  and the Preferred Stock will be duly and validly  authorized
and, when  executed and  delivered on behalf of the Company in  accordance  with
this  Agreement,  will be a valid  and  binding  obligation  of the  Company  in
accordance  with its  terms,  subject  to  general  principles  of equity and to
bankruptcy,   insolvency,  moratorium,  or  other  similar  laws  affecting  the
enforcement of creditors' rights generally.

           e.  Non-contravention.  The execution and delivery of this  Agreement
and the  Registration  Rights  Agreement  by the  Company,  the  issuance of the
Securities, and the consummation


                                        5





by the Company of the other  transactions  contemplated by this  Agreement,  the
Registration  Rights  Agreement,  and the  Preferred  Stock  do not and will not
conflict  with or  result  in a breach  by the  Company  of any of the  terms or
provisions  of, or constitute a default under (i) the articles of  incorporation
or by-laws of the  Company,  each as currently  in effect,  (ii) any  indenture,
mortgage,  deed of trust, or other material agreement or instrument to which the
Company is a party or by which it or any of its  properties or assets are bound,
including any listing agreement for the Common Stock except as herein set forth,
(iii) to its knowledge,  any existing applicable law, rule, or regulation or any
applicable  decree,  judgment,  or order of any court,  United States federal or
state regulatory body,  administrative agency, or other governmental body having
jurisdiction  over the Company or any of its  properties or assets,  or (iv) the
Company's listing agreement for its Common Stock,  except such conflict,  breach
or default which would not have a material  adverse  effect on the  transactions
contemplated herein.

           f.  Approvals.  No  authorization,  approval or consent of any court,
governmental body,  regulatory agency,  self-regulatory  organization,  or stock
exchange or market or the Stockholders of the Company is required to be obtained
by the  Company  for the  issuance  and sale of the  Securities  to the Buyer as
contemplated  by this  Agreement,  except  such  authorizations,  approvals  and
consents that have been obtained.

           g. SEC Filings. None of the Company's SEC Documents contained, at the
time they were filed,  any untrue  statement of a material fact or omit to state
any  material  fact  required  to be stated  therein  or  necessary  to make the
statements  made  therein in light of the  circumstances  under  which they were
made, not  misleading.  The Company has since September 1, 1996 timely filed all
requisite forms, reports and exhibits thereto with the SEC.

           h. Absence of Certain Changes.  Since January 1, 1997, there has been
no material adverse change and no material adverse  development in the business,
properties,  operations,  financial  condition,  or results of operations of the
Company, except as disclosed in Annex V or in the Company's SEC Documents.

           i. Full Disclosure. There is no fact known to the Company (other than
general economic conditions known to the public generally or as disclosed in the
Company's SEC  Documents),  that has not been  disclosed in writing to the Buyer
that (i) would  reasonably be expected to have a material  adverse effect on the
business  or  financial  condition  of the Company or (ii) would  reasonably  be
expected  to  materially  and  adversely  affect the  ability of the  Company to
perform its obligations  pursuant to this  Agreement,  the  Registration  Rights
Agreement,  the Joint Escrow  Instructions,  and the  Certificate of Designation
(collectively, the "Transaction Agreements").

           j. Absence of Litigation.  Except as set forth in Annex V hereto, and
in the  Company's  SEC  Documents,  which the Buyer  has  reviewed,  there is no
action,  suit,  proceeding,  inquiry  or  investigation  before or by any court,
public board or body pending or, to the knowledge


                                        6





of the  Company,  threatened  against  or  affecting  the  Company,  wherein  an
unfavorable decision,  ruling or finding would have a material adverse effect on
the  properties,  business  or  financial  condition  of  the  Company  and  its
subsidiaries  taken as a whole or the  transactions  contemplated  by any of the
Transaction   Agreements  or  which  would  adversely  affect  the  validity  or
enforceability  of, or the  authority  or ability of the  Company to perform its
obligations under, any of the Transaction Agreements.

           k.  Absence  of  Events  of  Default.  Except as set forth in Annex V
hereto and Section 3(e) hereof, no Event of Default (or its equivalent term), as
defined in the  respective  agreement  to which the  Company is a party,  and no
event  which,  with the giving of notice or the  passage of time or both,  would
become an Event of  Default  (or its  equivalent  term) (as so  defined  in such
agreement),  has occurred and is continuing,  which would reasonably be expected
to have a  material  adverse  effect on the  Company's  financial  condition  or
results of operations.

           Prior Issues.  Except as set forth in Annex V, during the twelve (12)
months  preceding  the date hereof,  the Company has not issued any  convertible
securities.  The presently outstanding unconverted principal amount of each such
issuance as at September 30, 1997 are set forth in Annex V.

           4. CERTAIN COVENANTS AND ACKNOWLEDGMENTS.

           a.  Transfer  Restrictions.  The  Buyer  acknowledges  that  (1)  the
Preferred Stock has not been and is not being registered under the provisions of
the 1933 Act and, except as provided in the Registration  Rights Agreement,  the
Shares have not been and are not being  registered  under the 1933 Act,  and may
not be  transferred  unless (A)  subsequently  registered  thereunder or (B) the
Buyer shall have  delivered  to the  Company an opinion of  counsel,  reasonably
satisfactory in form, scope and substance to the Company, to the effect that the
Securities to be sold or transferred  may be sold or transferred  pursuant to an
exemption  from  such  registration;  (2)  any  sale of the  Securities  made in
reliance  on Rule  144  promulgated  under  the  1933  Act  may be made  only in
accordance  with  the  terms  of said  Rule  and  further,  if said  Rule is not
applicable,  any  resale of such  Securities  under  circumstances  in which the
seller,  or the  person  through  whom the sale is made,  may be deemed to be an
underwriter,  as that term is used in the 1933 Act, may require  compliance with
some other  exemption under the 1933 Act or the rules and regulations of the SEC
thereunder;  and (3)  neither  the  Company  nor any  other  person is under any
obligation to register the Securities  (other than pursuant to the  Registration
Rights  Agreement) under the 1933 Act or to comply with the terms and conditions
of any exemption thereunder.

           b.  Restrictive  Legend.  The Buyer  acknowledges and agrees that the
Preferred  Stock,  and, until such time as the Common Stock has been  registered
under the 1933 Act as contemplated by the Registration Rights Agreement and sold
in accordance with an effective Registration  Statement,  certificates and other
instruments representing any of the Securities shall bear


                                        7




a restrictive  legend in  substantially  the following form (and a stop-transfer
order may be placed against transfer of any such Securities):

           THESE  SECURITIES (THE  "SECURITIES")  HAVE NOT BEEN REGISTERED UNDER
           THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR THE
           SECURITIES  LAWS OF ANY STATE AND MAY NOT BE SOLD OR OFFERED FOR SALE
           IN  THE  ABSENCE  OF AN  EFFECTIVE  REGISTRATION  STATEMENT  FOR  THE
           SECURITIES OR AN OPINION OF COUNSEL OR OTHER  EVIDENCE  ACCEPTABLE TO
           THE CORPORATION THAT SUCH REGISTRATION IS NOT REQUIRED.

           c. Registration  Rights Agreement.  The parties hereto agree to enter
into the  Registration  Rights  Agreement,  in  substantially  the form attached
hereto as Annex IV, on or before the Closing Date (as defined below).

           d. Filings.  The Company  undertakes and agrees to make all necessary
filings in connection  with the sale of the  Preferred  Stock to the Buyer under
any United States laws and regulations,  or by any domestic  securities exchange
or trading  market,  and to provide a copy thereof to the Buyer  promptly  after
such filing.

           e. Reporting  Status.  So long as the Buyer  beneficially owns any of
the Preferred  Stock,  the Company  shall file all reports  required to be filed
with the SEC  pursuant  to Section 13 or 15(d) of the 1934 Act,  and the Company
shall not terminate  its status as an issuer  required to file reports under the
1934 Act even if the 1934 Act or the  rules  and  regulations  thereunder  would
permit such  termination.  The Company will take all action under its control to
continue  the listing and trading of its Common Stock on The NASDAQ Stock Market
and will comply in all respects with the Company's  reporting,  filing and other
obligations under the by-laws or rules of the National Association of Securities
Dealers, Inc. ("NASD") or The NASDAQ Stock Market.

           f. Use of Proceeds.  The Company will use the proceeds  from the sale
of the Preferred Stock (excluding amounts paid by the Company for legal fees and
finder's fees in connection  with the sale of the Preferred  Stock) for internal
working  capital  purposes,  and shall not,  directly  or  indirectly,  use such
proceeds for any loan to or  investment  in any other  corporation,  partnership
enterprise or other person.

           g. Future Purchases.  (i) The Buyer  unconditionally  and irrevocably
agrees, at the option of the Company, to purchase the Additional Preferred Stock
consisting of an additional $640,000 liquidation amount of Convertible Preferred
Stock in one tranche (the "Additional Tranche"), on the terms and subject to the
conditions hereinafter provided.

                                        8





           (ii) The closing  for the  Additional  Tranche  shall occur on a date
(the "Additional Closing Date"), which date shall not be later than the ten (10)
days after the Effective Date (as defined below) or as otherwise mutually agreed
upon by the Company and the Buyer.  The closing of the Additional  Tranche shall
be  conducted  upon the same terms and  conditions  as those  applicable  to the
Initial Preferred Stock.

           (iii) The Buyer's  obligations to purchase the  Additional  Preferred
Stock is subject to the condition that, on the Additional  Closing Date, (A) the
Registration  Statement  required  to be filed  under  the  Registration  Rights
Agreement  shall  continue  to be  effective,  and (B) the  representations  and
warranties  of the  Company  contained  in  Section  3 hereof  shall be true and
correct  in all  material  respects  on the  Additional  Closing  Date  (and the
Company's  issuance  of the  Additional  Preferred  Stock shall  constitute  the
Company's making each such representation and warranty as of such date).

           (iv) The  Additional  Preferred  Stock shall be governed by the terms
and provisions of the Certificate of Designation as if such Additional Preferred
Stock was issued on the date the Initial Preferred Stock was issued.

           h. Certain  Agreements.  (i) The Company covenants and agrees that it
will not,  without  the prior  written  consent  of the  Buyer,  enter  into any
subsequent or further  offer or sale of Common Stock or  securities  convertible
into  Common  Stock  with any third  party  ("Subsequent  Financing")  until the
earlier of (a) the date which is forty-five  (45) days after the Effective  Date
(as defined  below) or (b) the date on which 85% of the  Preferred  Stock shares
have been converted into shares of Common Stock.  Notwithstanding the foregoing,
the  Company may enter into a  Subsequent  Financing  without the prior  written
consent of the Buyer if such  Subsequent  Financing  is exempt  from  securities
registration  under Regulation D and the Company is not required to register the
underlying  securities  within the later of one hundred twenty (120) days of the
Effective  Date (as defined  below),  or one hundred  eighty (180) days from the
Closing Date.

           (ii)  Subject  to  the  conditions  of  subparagraph   (h)(iii),  the
provisions  of  subparagraph  (h)(i)  will  not  apply  to (x) the  issuance  of
securities  (other than for cash) in  connection  with a merger,  consolidation,
sale of assets, disposition or (y) the exchange of the capital stock for assets,
stock or other joint venture interests.

           (iii) Any action  contemplated under subparagraph  (h)(ii) is subject
to the condition  that  registration  rights,  if any, in  connection  with such
action  shall not require the filing of a  Registration  Statement in respect of
such stock prior to thirty (30) days after the Effective Date.

           (iv)  The term  "Effective  Date"  means  the  effective  date of the
Registration  Statement  covering the Registrable  Securities (as defined in the
Registration Rights Agreement).


                                        9





           i. Available  Shares.  The Company shall have at all times authorized
and reserved for issuance,  free from preemptive rights,  shares of Common Stock
sufficient to yield the number of shares of Common Stock  issuable at conversion
as may be required to satisfy the conversion rights of the Buyer pursuant to the
terms and conditions of the Preferred Stock.

           j.  Dilution.  The  Company  acknowledges  that the  number of Shares
issuable upon  conversion of the Preferred Stock may increase  substantially  in
certain circumstances,  including, but not limited to, when the trading price of
the Common Stock  declines  prior to a  conversion  and that the issuance of the
Shares upon such a conversion of the Preferred  Stock may have a dilutive effect
of the ownership interest of the other shareholders of the Company.

           k. Registered Offering.  Notwithstanding anything in the foregoing to
the contrary,  the Company shall be permitted,  upon prior written notice to the
Buyer,  to issue and sell its Common Stock or securities,  convertible  into its
Common Stock in a registered  offering (the  "Registered  Offering"),  provided,
that the proceeds of such Registered  Offering shall be applied solely to redeem
the  Preferred  Stock  in  accordance  with  the  terms  of the  Certificate  of
Designation.

           l. Other Buyers.  The Company shall be permitted to issue and sell up
to three hundred sixty (360) additional  shares of Preferred Stock to affiliates
of the  Company or to persons  who do not  beneficially  own more than five (5%)
percent of the outstanding shares of Common Stock.

           5. TRANSFER AGENT INSTRUCTIONS.

           a.  Promptly  following  the  delivery by the Buyer of the  aggregate
purchase price for the Initial  Preferred  Stock in accordance with Section 1(c)
hereof, the Company will irrevocably instruct its transfer agent to issue Common
Stock from time to time upon  conversion of the Preferred  Stock in such amounts
as specified from time to time by the Company to the transfer agent, bearing the
restrictive  legend  specified  in  Section  4(b) of  this  Agreement  prior  to
registration  of the Shares  under the 1933 Act,  registered  in the name of the
Buyer or its nominee and in such  denominations  to be specified by the Buyer in
connection with each  conversion of the Preferred  Stock.  The Company  warrants
that no instruction other than such  instructions  referred to in this Section 5
and stop  transfer  instructions  to give effect to Section 4(a) hereof prior to
registration  and  sale of the  Shares  under  the 1933 Act will be given by the
Company to the  transfer  agent and that the Shares  shall  otherwise  be freely
transferable  on the books  and  records  of the  Company  as and to the  extent
provided in this Agreement,  the Registration  Rights Agreement,  and applicable
law. Nothing in this Section shall affect in any way the Buyer's obligations and
agreement  to comply  with all  applicable  securities  laws upon  resale of the
Securities.  If the Buyer  provides  the  Company  with an  opinion  of  counsel
reasonably  satisfactory  to the Company  that  registration  of a resale by the
Buyer of any of the Securities in accordance  with clause (1)(B) of Section 4(a)
of this Agreement is not required


                                       10





under the 1933 Act,  the  Company  shall  (except as  provided  in clause (2) of
Section 4(a) of this  Agreement)  permit the transfer of the Securities  and, in
the case of the Shares,  promptly instruct the Company's transfer agent to issue
one or more  certificates  for Common Stock  without  legend in such name and in
such denominations as specified by the Buyer.

           b. The Company will permit the Buyer to exercise its right to convert
the  Preferred  Stock  by  telecopying  an  executed  and  completed  Notice  of
Conversion  to the  Company  and  delivering  within  three  (3)  business  days
thereafter,  the original Notice of Conversion and the certificates representing
the Preferred  Stock being converted to the Company by express  courier,  with a
copy to the  transfer  agent.  Each  date on which a  Notice  of  Conversion  is
telecopied  to and  received by the Company in  accordance  with the  provisions
hereof  shall be  deemed a  Conversion  Date.  The  Company  will  transmit  the
certificates  representing  the Converted Shares issuable upon conversion of any
Preferred Stock (together with certificates representing the Preferred Stock not
being so converted) to the Buyer via express courier,  by electronic transfer or
otherwise,  within three (3) business  days after  receipt by the Company of the
original  Notice of Conversion and the  certificate  representing  the Preferred
Stock being converted (the "Delivery Date").

           c. The Company understands that a delay in the issuance of the Shares
of Common Stock beyond the  Delivery  Date could result in economic  loss to the
Buyer.  As  compensation  to the Buyer for such loss,  the Company agrees to pay
late  payments  to the Buyer for late  issuance  of Shares  upon  Conversion  in
accordance  with the  following  schedule  (where  "No.  Business  Days Late" is
defined  as the number of  business  days  beyond  five (5)  business  days from
Delivery Date);  provided,  however,  the Company shall not be obligated to make
any payment under this Section if the cause of such delay in the issuance of the
Shares of Common  Stock is not caused by the Company or is the result of an act,
omission or circumstance beyond the control of the Company.

                                        Late Payment For Each
                                        $10,000 of Initial Preferred Stock
    No. Business Days Late              Principal Amount Being Converted

               1                                  $100
               2                                  $200
               3                                  $300
               4                                  $400
               5                                  $500
               6                                  $600
               7                                  $700
               8                                  $800
               9                                  $900
               10                                 $1,000
               >10                                $1,000 +$200 for each Business
                                                  Day Late beyond 10 days


                                       11





The Company shall pay any payments  incurred  under this Section in  immediately
available  funds upon demand.  Nothing  herein shall limit the Buyer's  right to
pursue actual damages for the Company's  failure to issue and deliver the Common
Stock to the Buyer. Furthermore,  in addition to any other remedies which may be
available  to the Buyer,  in the event that the Company  fails for any reason to
effect  delivery of such shares of Common Stock  within five (5)  business  days
after the  Delivery  Date,  the Buyer will be  entitled  to revoke the  relevant
Notice  of  Conversion  by  delivering  a notice to such  effect to the  Company
whereupon  the Company and the Buyer shall each be restored to their  respective
positions immediately prior to delivery of such Notice of Conversion.

           d. In lieu  of  delivering  physical  certificates  representing  the
Common Stock issuable upon conversion,  provided the Company's transfer agent is
participating in the Depository Trust Company ("DTC") Fast Automated  Securities
Transfer  program,  upon  request  of the  Buyer  and its  compliance  with  the
provisions contained in this paragraph,  so long as the certificates therefor do
not  bear a legend  and the  Buyer  thereof  is not  obligated  to  return  such
certificate  for the  placement of a legend  thereon,  the Company shall use its
best efforts to cause its transfer agent to  electronically  transmit the Common
Stock issuable upon  conversion to the Buyer by crediting the account of Buyer's
Prime Broker with DTC through its Deposit Withdrawal Agent Commission system.

           6. DELIVERY INSTRUCTIONS.

           The Initial Preferred Stock or the Additional Preferred Stock, as the
case may be, shall be  delivered by the Company to the Escrow Agent  pursuant to
Section 1(b) hereof,  on a delivery  against  payment basis, on the Closing Date
and on the Additional Closing Date, respectively..

           7. CLOSING DATE.

           The date and time of the issuance  and sale of the Initial  Preferred
Stock (the "Closing Date") shall occur no later than 1:00 P.M., New York time on
the  first  NYSE  trading  day after the  fulfillment  or waiver of all  closing
conditions  pursuant to Sections 8 and 9, or such other mutually agreed to time.
The date of the  Additional  Closing Date shall be the date  specified by either
party upon at least five (5) business  days' advance  notice to the other party;
provided,  however,  that it shall be a condition of the Additional Closing Date
that (i) the  conditions  of  Section  4(g) be  satisfied,  and (ii) each of the
conditions  contemplated by Sections 8 and 9 hereof shall have been satisfied or
waived on or before  such date.  Each  closing  shall  occur on such date at the
offices of the Escrow Agent.  Notwithstanding anything to the contrary contained
herein,  the Escrow Agent will be authorized to release the Escrow Property only
upon satisfaction of the conditions set forth in Sections 8 and 9 hereof.

           8. CONDITIONS TO THE COMPANY'S OBLIGATION TO SELL.


                                       12





           The  Buyer  understands  that the  Company's  obligation  to sell the
Initial  Preferred Stock on the Closing Date and the Additional  Preferred Stock
on the Additional Closing Date is conditioned upon:

           a. The receipt and  acceptance by the Buyer of this  Agreement (to be
evidenced by the Buyer's  execution and delivery of this Agreement) for the sale
of the Preferred Stock;

           b. Delivery by the Buyer to the Escrow Agent of good funds as payment
in full of an  amount  equal to the  relevant  purchase  price  for the  Initial
Preferred  Stock or the  Additional  Preferred  Stock,  as the  case may be,  in
accordance with Section 1(c) hereof;

           c. The accuracy on the Closing Date or the  Additional  Closing Date,
as the case may be, of the representations and warranties of the Buyer contained
in this  Agreement,  each as if made on such date,  and the  performance  by the
Buyer on or  before  such  date of all  covenants  and  agreements  of the Buyer
required to be performed on or before such date;

           d.  There  shall  not  be in  effect  any  law,  rule  or  regulation
prohibiting or restricting the transactions  contemplated  hereby,  or requiring
any consent or approval which shall not have been obtained.

           9. CONDITIONS TO THE BUYER'S OBLIGATION TO PURCHASE.

           The Company  understands that the Buyer's  obligation to purchase the
Initial  Preferred Stock on the Closing Date and the Additional  Preferred Stock
on the Additional Closing Date is conditioned upon:

           a. The receipt and acceptance by the Company of this Agreement  (such
acceptance  to be  evidenced  by the  Company's  execution  and delivery of this
Agreement) for the sale of at least Three Million Dollars ($3,000,000.00) on the
Closing  Date,  and Six Hundred  Forty  Thousand  Dollars  ($640,000.00)  on the
Additional  Closing Date in liquidation value of Preferred Stock (or such lesser
amount as the Company, in its sole discretion, shall determine);

           b.  Delivery  by the  Company  to the  Escrow  Agent  of the  Initial
Preferred  Stock or the  Additional  Preferred  Stock,  as the  case may be,  in
accordance with this Agreement;

           c. The accuracy in all  material  respects on the Closing Date or the
Additional  Closing  Date,  as the  case  may  be,  of the  representations  and
warranties of the Company  contained in this Agreement,  each as if made on such
date, and the performance by the Company on or before such date of all covenants
and  agreements of the Company  required to be performed on or before such date;
and



                                       13





           d. On the Closing Date or the  Additional  Closing  Date, as the case
may be, the Buyer shall have received (i) an opinion of counsel for the Company,
dated such date, in form,  scope and substance  reasonably  satisfactory  to the
Buyer,  to the  effect  set forth in Annex  III  attached  hereto,  and (ii) the
Registration Rights Agreement duly executed and delivered by the Company.

           10. GOVERNING LAW: MISCELLANEOUS.

           a. This Agreement  shall be governed by and interpreted in accordance
with the laws of the State of New York without  giving effect to the  principles
thereof  regarding  the  conflict of laws.  Each of the parties  consents to the
jurisdiction  of the federal  courts whose  districts  encompass any part of the
City of New York or the state  courts of the  State of New York  sitting  in the
City of New York in connection with any dispute arising under this Agreement and
hereby waives, to the maximum extent permitted by law, any objection,  including
any  objection  based on  forum  non  conveniens,  to the  bringing  of any such
proceeding in such jurisdictions.

           b. A facsimile  transmission of this signed  Agreement shall be legal
and binding on all parties hereto.

           c. This Agreement may be signed in one or more counterparts,  each of
which shall be deemed an original.

           d. The headings of this  Agreement are for  convenience  of reference
and shall not form part of, or affect the interpretation of, this Agreement.

           e.  If  any  provision  of  this   Agreement   shall  be  invalid  or
unenforceable in any jurisdiction, such invalidity or unenforceability shall not
affect the validity or  enforceability of the remainder of this Agreement or the
validity or enforceability of this Agreement in any other jurisdiction.  

           f. This  Agreement  may be amended only by an  instrument  in writing
signed by the party to be charged with enforcement thereof.

           g. This Agreement  supersedes all prior agreements and understandings
among the parties hereto with respect to the subject matter hereof.

           11.  NOTICES.  Any notice  required or permitted  hereunder  shall be
given in  writing  (unless  otherwise  specified  herein)  and  shall be  deemed
effectively given on the earliest of

           (i) the date delivered,  if delivered by personal delivery as against
           written receipt therefor or by confirmed facsimile  transmission,  if
           received during normal business hours,


                                       14





           (ii) the seventh business day after deposit,  postage prepaid, in the
           United States Postal Service by registered or certified mail, or

           (iii) the third business day after mailing by  international  express
           courier, with delivery costs and fees prepaid,

in each case,  addressed to each of the other parties thereunto  entitled at the
following  addresses (or at such other  addresses as such party may designate by
ten (10)  days'  advance  written  notice  similarly  given to each of the other
parties hereto):

COMPANY:                       XYBERNAUT CORPORATION
                               12701 Fair Lakes Circle
                               Suite 550
                               Fairfax, Virginia 22033
                               ATTN: Steven A. Newman
                               Telecopier No.: (703) 631-6734
                               Telephone No.: (703) 631-6925

                               with a copy to:

                               Parker Chapin Flattau & Klimpl, LLP
                               1211 Avenue of the Americas
                               New York, New York 10036
                               Attention: Martin Eric Weisberg, Esq.
                               Telecopier No.:  (212) 704-6288

BUYER:                         At the address set forth on the signature page of
                               this Agreement.

ESCROW AGENT:                  Krieger & Prager, Esqs.
                               319 Fifth Avenue
                               New York, New York 10016
                               Telecopier No. (212) 213-2077

           12.  SURVIVAL  OF  REPRESENTATIONS  AND  WARRANTIES.   The  Company's
representations  and warranties  herein shall survive the execution and delivery
of this  Agreement  and the  delivery of the  Preferred  Stock and the  Purchase
Price,  and shall  inure to the  benefit  of the Buyer  and its  successors  and
assigns.

           [BALANCE OF PAGE INTENTIONALLY LEFT BLANK.]
           IN WITNESS  WHEREOF,  this  Agreement  has been duly  executed by the
Buyer or one of its officers  thereunto duly authorized as of the date set forth
below.

NUMBER OF SHARES OF
INITIAL PREFERRED STOCK TO BE PURCHASED:                                  3,000


                                       15





AGGREGATE PURCHASE PRICE OF
SUCH INITIAL PREFERRED STOCK:                                        $3,000,000

NUMBER OF SHARES OF ADDITIONAL
PREFERRED STOCK TO BE PURCHASED:                                            640

AGGREGATE PURCHASE PRICE OF SUCH
ADDITIONAL PREFERRED STOCK:                                            $640,000


                             SIGNATURES FOR ENTITIES

           IN WITNESS  WHEREOF,  the  undersigned  represents that the foregoing
statements are true and correct and that it has caused this Securities  Purchase
Agreement   to  be  duly   executed   on  its  behalf  this   ________   day  of
___________________, 1997.


- --------------------------------            -----------------------------------
Address                                      Printed Name of Subscriber

- --------------------------------
                                             By: ------------------------------
Telecopier No. ------------------             (Signature of Authorized Person)

- --------------------------------             ----------------------------------
Jurisdiction of Incorporation                  Printed Name and Title
or Organization

As of the date set forth below,  the undersigned  hereby accepts this Agreement
and  represents  that the foregoing  statements are true and correct and that it
has caused this Securities Purchase Agreement to be duly executed on its behalf.

XYBERNAUT CORPORATION

By:
   ---------------------------
Title:
       -----------------------
Date:
       -----------------------






           ANNEX I           CERTIFICATE OF AMENDMENT TO THE CERTIFICATE OF
                             INCORPORATION/CERTIFICATE OF DESIGNATIONS

           ANNEX II          JOINT ESCROW INSTRUCTIONS

           ANNEX III         OPINION OF COUNSEL

           ANNEX IV          REGISTRATION RIGHTS AGREEMENT

           ANNEX V           COMPANY DISCLOSURE MATERIALS






                                                                       ANNEX V

                               COMPANY DISCLOSURE
                               ------------------






                                [TO BE SUPPLIED]