Exhibit 4.2

THESE SECURITIES HAVE NOT BEEN REGISTERED WITH THE UNITED STATES  SECURITIES AND
EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE OR OTHER POLITICAL
SUBDIVISION OF THE UNITED STATES. THESE SECURITIES ARE BEING OFFERED PURSUANT TO
AN  EXEMPTION  FROM  REGISTRATION  UNDER  REGULATION  D  PROMULGATED  UNDER  THE
SECURITIES ACT OF 1933, AS AMENDED (THE  "SECURITIES  ACT").  THE SECURITIES ARE
"RESTRICTED"  AND MAY NOT BE  RESOLD,  TRANSFERRED  OR  OFFERED  FOR  RESALE  OR
TRANSFER OR PLEDGED OR HYPOTHECATED,  EXCEPT AS PERMITTED UNDER THE ACT PURSUANT
TO REGISTRATION OR EXEMPTION  THEREFROM.  THIS SUBSCRIPTION  AGREEMENT SHALL NOT
CONSTITUTE AN OFFER TO SELL NOR A SOLICITATION OF AN OFFER TO BUY THE SECURITIES
IN ANY JURISDICTION IN WHICH SUCH OFFER OR SOLICITATION WOULD BE UNLAWFUL.

                 5% CONVERTIBLE PREFERRED STOCK AND COMMON STOCK

                               PURCHASE AGREEMENT

                              XYBERNAUT CORPORATION

            THIS  AGREEMENT  is made as of the  15th  day of  May,  1998,  among
Xybernaut  Corporation,   Nasdaq  Symbol  "XYBR"  (the  "Company"),  a  Delaware
corporation,  with its principal office at 12701 Four Lakes Circle,  Fairfax, VA
22033,  and  Libertyview  Plus Fund,  Libertyview  Fund, LLC and CPR (USA) Inc.,
(each a  "Purchaser"),  with their principal  office at c/o Libertyview  Capital
Management, 101 Hudson Street, Suite 3700, Jersey City, New Jersey 07302.

            IN  CONSIDERATION   of  the  mutual  covenants   contained  in  this
Agreement, the Company and the Purchaser agree as follows:

            Section 1. Certain Definitions. For purposes of this Agreement:

            "Agreement"  means this 5%  Convertible  Preferred  Stock and Common
Stock Purchase Agreement.

            "Closing  Date"  means  the date  agreed to by the  parties  for the
delivery of the original stock certificate  against a wire transfer of the funds
to the Company.

            "Closing"  means  the  completion  of the  purchase  and sale of the
Shares on the Closing Date.

            "Common  Shares"  means the shares of Common  stock being issued and
sold pursuant to Section 2.2 hereof.

            "Common  Stock"  means the Common  Stock of the  Company,  $0.01 par
value per share.

            "Conversion  Date"  means  the  date  on  which  the  Purchaser  has
telecopied the Notice of Conversion to the Company.






            "Convertible Preferred Stock" means the shares of Series C Preferred
Stock of the Company convertible into Common Stock of the Company as hereinafter
provided;  including the  Certificate  of Designation  designating  the Series C
Preferred Stock.

            "Conversion  Price"  means an amount  equal to the lesser of (a) 100
percent of the  average  closing  bid price of the Common  Stock as  reported by
NASDAQ or any  successor  exchange  in which the Common  Stock is listed for the
five (5)  trading  days  preceding  the  Conversion  Date,  or (b) Four  ($4.00)
Dollars.

            "Conversion Shares" means the shares of Common Stock issued upon the
conversion of the Convertible Preferred Stock.

            "Purchase  Price" means the aggregate  purchase  price of the Shares
purchased.

            "Shares"  means,  collectively,  the  shares  of Common  Shares  and
Convertible Preferred Stock purchased pursuant to this Agreement.

            Section 2.   Authorization and Sale of Shares.

            2.1   Authorization.  Subject  to the terms and  conditions  of this
Agreement, the Company has authorized the sale and issuance of the Shares.

            2.2   Agreement to Sell and Purchase the Shares.  The offer and sale
of the  Shares are being made  hereunder  in  reliance  upon the  provisions  of
Regulation  D  promulgated  under the  Securities  Act of 1933,  as amended (the
"Securities  Act").  The Company will sell and the Purchasers will buy Shares in
reliance upon the  representations  and warranties of the Company and Purchasers
contained  in this  Agreement,  upon the terms and  conditions  hereinafter  set
forth, 110,294 shares of Common Stock at a price of $3.40 per share (the "Common
Shares"),  for an  aggregate  purchase  price  of  $375,000  and 375  shares  of
Convertible Preferred Stock for an aggregate purchase price of $375,000 based on
the purchase price of $1,000 per share.  The  Convertible  Preferred Stock shall
pay a 5% cumulative dividend,  payable in cash or Common Stock at the Conversion
Price,  at the discretion of the Company,  at the time of each  conversion.  The
purchase and sale of the Shares shall occur on the Closing Date.

            2.3   Time and Place of Closing.  The  Closing  shall be held at the
offices of Parker Chapin Flattau & Klimpl, LLP ("Escrow Agent"),  1211 Avenue of
the Americas, New York, NY 10036, as promptly as practicable as agreed to by the
parties to this Agreement.

            2.4   Payment  and  Delivery.  At  or  prior  to  the  Closing,  the
following shall occur:

                  (a)   Purchasers  shall remit by wire  transfer  the  Purchase
Price to Escrow  Agent  pursuant to the Escrow  Agreement,  dated May 15,  1998,
among the  Company,  Purchasers  and  Escrow  Agent  (the  "Escrow  Agreement"),
attached hereto as Attachment 1, as payment in full for the Shares.

                  (b)   Company shall deliver or cause to be delivered to Escrow
Agent a certificate representing the Shares, registered in the name of Purchaser
(or any nominee  designated by Purchaser on the Closing Date), free and clear of
all liens, claims, charges and encumbrances.

                  (c)   Wire  instructions  for Parker Chapin  Flattau & Klimpl,
LLP are as follows:


                                       2




                     Citibank, N.A.

                     ABA No. 021000089

                     For Further Credit to

                     Parker Chapin Flattau & Klimpl, LLP, Attorney Trust Account

                     Account No. 37432544

All  subscription  funds shall be held in escrow by the Escrow Agent pursuant to
the terms and  conditions set forth in the Escrow  Agreement  among the Company,
the Purchasers and the Escrow Agent.

            Section 3. General  Representations  and  Warranties of the Company.
The  Company  hereby  represents  and  warrants  to,  and  covenants  with,  the
Purchasers  that the following are true and correct as of the date hereof and as
of the Closing Date.

            3.1   Organization; Qualification. The Company is a corporation duly
organized and validly existing under the laws of the State of Delaware and is in
good standing under such laws. The Company has all requisite corporate power and
authority to own, lease and operate its  properties and assets,  and to carry on
its business as presently conducted.  The Company is qualified to do business as
a  foreign  corporation  in each  jurisdiction  in which  the  ownership  of its
property or the nature of its business requires such qualification, except where
failure to so qualify would not have a material adverse effect on the Company.

            3.2   Capitalization.  The  authorized  capital stock of the Company
consists of 40,000,000  shares of Common Stock,  $0.01 par value per share,  and
6,000,000 shares of nonvoting  Preferred Stock, $0.01 par value, of 3,000 shares
have been designated  Series A Convertible  Preferred Stock, par value $0.01 per
share,  4,180 have been designated as Series B Convertible  Preferred Stock, par
value  $.01 per  share,  and 375 have been  designated  as Series C  Convertible
Preferred  Stock,  par value $.01 per share.  As of May 15,  1998,  none of such
Series A or Series B Preferred Stock is outstanding.  All issued and outstanding
shares of Common  Stock have been duly  authorized  and  validly  issued and are
fully paid and  nonassessable.  The Company will reserve from its authorized but
unissued shares of Common Stock a sufficient number of shares of Common Stock to
permit the conversion in full of the Convertible Preferred Stock subject of this
Agreement. As of the Closing Date, the Company had reserved sufficient shares of
Common Stock for issuance upon exercise of the Convertible Preferred Stock which
are convertible,  at Purchaser's option, at the Conversion Price, as per Section
9 of this Agreement.

            3.3   Authorization.  The Company has all requisite corporate right,
power and authority to execute and deliver this  Agreement and to consummate the
transactions  contemplated  hereby.  All  corporate  action  on the  part of the
Company,  its  directors  and  stockholders  necessary  for  the  authorization,
execution,  delivery and  performance  of this  Agreement  by the  Company,  the
authorization,  sale, issuance and delivery of the Shares and the performance of
the Company's obligations hereunder has been taken. This Agreement has been duly
executed and delivered by the Company and constitutes a legal, valid and binding
obligation of the Company  enforceable in accordance with its terms,  subject to
laws of general application relating to bankruptcy, insolvency and the relief of
debtors and rules of law governing  specific  performance,  injunctive relief or
other equitable remedies,  and to limitations of public policy as they may apply
to the  indemnification  provisions set forth in Section 7.3 of this  Agreement.
Upon their issuance and delivery pursuant to this


                                       3




Agreement,  the Shares will be validly issued,  fully paid and nonassessable and
will be free of any liens or encumbrances;  provided,  however,  that the Shares
are subject to  restrictions  on transfer under state and/or federal  securities
laws.  The issuance and sale of the Shares will not give rise to any  preemptive
right or right of first  refusal  or right of  participation  on  behalf  of any
person.

            3.4   No Conflict.  The execution and delivery of this  Agreement do
not, and the  consummation  of the  transactions  contemplated  hereby will not,
conflict  with,  or result in any  violation  of, or default,  or give rise to a
right of termination, cancellation or acceleration of any material obligation or
to a loss of a  material  benefit,  under,  any  provision  of the  Articles  of
Incorporation,  and any amendments thereto, Bylaws,  Stockholders Agreements and
any amendments thereto of the Company or any material mortgage, indenture, lease
or other  agreement  or  instrument,  permit,  concession,  franchise,  license,
judgment,  order, decree statute, law, ordinance,  rule or regulation applicable
to the Company, its properties or assets and which would have a material adverse
effect on the Company's business and financial condition.

            3.5   Accuracy  of Reports and  Information.  The Company is in full
compliance,  to the extent  applicable,  with all  reporting  obligations  under
either Section 12(b), 12 (g) or 15(d) of the Securities Exchange Act of 1934, as
amended  (the  "Exchange  Act").  The Company has  registered  its Common  Stock
pursuant to Section 12 of the  Exchange  Act and the Common  Stock is listed and
trades on the Nasdaq National Small Cap Market.

            The Company has filed all material  required to be filed pursuant to
all reporting  obligations,  under either Section 13(a) or 15(d) of the Exchange
Act for a period of at least twelve (12) months immediately  preceding the offer
to sale of the Shares (or for such  shorter  period  that the  Company  has been
required to file such material).

            3.6   SEC Filings/Full Disclosure. Since completion of the Company's
initial  public  offering in July 1996,  none of the Company's  filings with the
Securities and Exchange  Commission  contain 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  therein in light of the  circumstances  under
which they were made, not misleading. The Company has timely filed all requisite
forms, reports and exhibits thereto with the Securities and Exchange Commission.

            There is no fact known to the Company  (other than general  economic
conditions known to the public generally) that has not been disclosed in writing
to the  Purchasers  which (i) could  reasonably  be  expected to have a material
adverse effect on the business or financial  condition,  properties or assets of
the Company,  or (ii) could  reasonably be expected to materially  and adversely
affect the ability of the Company to perform  its  obligations  pursuant to this
Agreement.

            3.7   Absence  of  Undisclosed  Liabilities.   The  Company  has  no
material liabilities or obligations,  absolute or contingent (individually or in
the aggregate),  except as set forth in the financial  statements or as incurred
in the ordinary course of business after the date of the financial statements.

            3.8   Governmental   Consent,   etc.   No   consent,   approval   or
authorization  of or  designation,  declaration or filing with any  governmental
authority  on the part of the Company is required in  connection  with the valid
execution and delivery of this Agreement,  or the offer, sale or issuance of the
Shares, or the consummation of any other transaction contemplated hereby, except
the filing with the SEC of a registration


                                       4




statement  on Form S-3 for the  purpose of  registering  the  Conversion  Shares
underlying the Convertible Preferred Stock.

            3.9   Intellectual  Property Rights. Except as disclosed in the Form
10-KSB, Form 10-QSBs and Form 8-Ks filed by the Company for a period of at least
twelve (12) months immediately preceding this offer (the "Reports"), the Company
has sufficient trademarks,  trade names, patent rights,  copyrights and licenses
to conduct its business as presently  conducted in the Reports. To the Company's
knowledge,  neither the Company nor its products is  infringing or will infringe
any trademark,  trade name, patent right,  copyright,  license,  trade secret or
other  similar  right of others  currently in  existence;  and there is no claim
being made against the Company  regarding  any  trademark,  trade name,  patent,
copyright,  license,  trade secret or other  intellectual  property  right which
could have a material  adverse effect on the business or financial  condition of
the Company.

            3.10  Material  Contracts.  Except as set forth in the Reports,  the
agreements  to which the Company is a party  described  in the Reports are valid
agreements,  in full force and effect the Company is not in  material  breach or
material default under any of such agreements.

            3.11  Litigation.  Except as disclosed  in the Reports,  there is no
action,  proceeding or  investigation  pending,  or to the  Company's  knowledge
threatened,  against the Company which might result,  either  individually or in
the  aggregate,  in any  material  adverse  change in the  business,  prospects,
conditions,  affairs or operations of the Company. The Company is not a party to
or subject to the provisions of any order, writ, injunction,  judgment or decree
of any court or government agency or instrumentality.

            3.12  Title to  Assets.  Except  as set  forth in the  Reports,  the
Company has good and  marketable  title to all  properties  and material  assets
described  in the Reports as owned by it,  free and clear of any  pledge,  lien,
security interest,  encumbrance,  claim or equitable interest other than such as
are not material to the business of the Company.

            3.13  Subsidiaries.  Except as disclosed in the Reports, the Company
does not presently own or control,  directly or indirectly,  any interest in any
other corporation, partnership, association or other business entity.

            3.14  Required Governmental Permits. The Company is in possession of
and operating in compliance  with all  authorizations,  licenses,  certificates,
consents,   orders  and  permits  from  state,   federal  and  other  regulatory
authorities which are material to the conduct of its business,  all of which are
valid and in full force and effect.

            3.15  Listing.  The Company will  maintain the listing of its Common
Stock on the Nasdaq National Small Cap Market or other  organized  United States
market or Quotation system.

            3.16  Other  Outstanding  Securities/Financing  Restrictions.  Other
than warrants and options to acquire  shares of Common Stock as disclosed in the
Reports,  there are no other  outstanding  securities  debt or equity  presently
convertible  into  Common  Stock.  Other than as set forth in the  Reports,  the
Company has no  outstanding  restricted  shares,  or shares of Common Stock sold
under  Regulation S, Regulation D or outstanding  under any other exemption from
registration,  which are available  for sale as  unrestricted  ("free  trading")
stock.


                                       5




            3.17  Legal Opinion.  Purchasers shall, upon purchase of the Shares,
receive  an  opinion  letter  from  counsel  to the  Company,  and  the  Company
represents that it will  immediately  obtain such an opinion from counsel to the
satisfaction of the Transfer Agent, to the effect that:

                  (i)   The Company is incorporated  and validly existing in the
jurisdiction of its incorporation.  The Company and/or its subsidiaries are duly
qualified to do business as a foreign corporation and is in good standing in all
jurisdictions  where the Company and/or  subsidiaries owns or leases properties,
maintains employees or conducts business,  except for jurisdictions in which the
failure to so qualify would not have a material  adverse  effect on the Company,
and has all requisite  corporate  power and authority to own its  properties and
conducts its business.

                  (ii)  There is no action, proceeding or investigation pending,
or to such  counsel's  knowledge,  threatened  against the  Company  which might
result, either individually or in the aggregate,  in any material adverse change
in the business or financial condition of the Company.

                  (iii) To counsel's knowledge, the Company is not a party to or
subject to the provisions of any order, writ, injunction,  judgment or decree of
any court or government agency or instrumentality.

                  (iv)  To  counsel's  knowledge,  there  is  no  action,  suit,
proceeding or investigation by the Company currently pending.

                  (v)   The Common Shares and the Convertible  Preferred  Stock,
which shall be issued at the Closing,  are duly  authorized  and validly  issued
under the Company's Certificate of Incorporation.

                  (vi)  This  Purchase  Agreement,  the  issuance  of the Common
Shares, the Convertible Preferred Stock and the Conversion Shares have been duly
approved by all required  corporate  action and that all such  securities,  upon
delivery, shall be validly issued and outstanding, fully paid and nonassessable.

                  (vii) The   issuance  of  the  Shares  will  not  violate  the
applicable listing agreement between the Company and any securities  exchange or
market on which the Company's securities are listed.

                  (viii)Assuming   the  accuracy  of  the   representation   and
warranties  of the  Company  and the  Purchasers  set  forth  in  this  Purchase
Agreement,  the offer,  issuance and sale of the Common Shares,  the Convertible
Preferred  Stock  and the  Conversion  Shares  to be  issued  to the  Purchasers
pursuant  to  this  Purchase   Agreement,   are  exempt  from  the  registration
requirements of the Securities Act.

            3.18  Use of Proceeds.  The Company represents that the net proceeds
from this offering will be used for general corporate purposes.

            3.19  Dilution.   The  Company  is  aware  and   acknowledges   that
conversion of the  Convertible  Preferred Stock could cause dilution to existing
shareholders and could  significantly  increase the outstanding number of shares
of Common Stock.

            Section  4.   Representations,   Warranties  and  Covenants  of  the
Purchasers . Each Purchaser  represents and warrants to, and covenants with, the
Company that the  following are true and correct as of the date hereof and as of
the Closing Date.


                                       6




            4.1   Authority.  The  Purchaser's  signatory has all right,  power,
authority  and capacity to execute and deliver this  Agreement and to consummate
the transactions  contemplated hereby. This Agreement has been duly executed and
delivered by the  Purchaser  and will  constitute  the legal,  valid and binding
obligations of the Purchaser,  enforceable in accordance with its terms, subject
to laws of general application relating to bankruptcy, insolvency and the relief
of debtors and rules of law governing specific performance, injunctive relief or
other equitable remedies,  and to limitations of public policy as they may apply
to the indemnification provisions set forth in Section 7.3 of this Agreement.

            4.2   Investment  Experience.  Purchaser is an "accredited investor"
as defined in Rule 501(a) under the  Securities  Act.  Purchaser is aware of the
Company's  business  and  financial  condition  and  has had  access  to and has
acquired  sufficient  information about the Company,  including the Reports,  to
reach an informed and  knowledgeable  decision to acquire the Shares.  Purchaser
has  such  business  and  financial  experience  as is  required  to give it the
capacity to protect its own  interests  in  connection  with the purchase of the
Shares.  Purchaser  has the  ability to bear the  economic  risk of  Purchaser's
investment pursuant to this Purchase Agreement. Purchaser has not been organized
for the  purpose of  investing  in  securities  of the  Company,  although  such
investment is consistent with Purchaser's purpose.

            4.3   Investment Intent.  Without limiting its ability to resell the
Shares  and  the  Conversion  Shares  pursuant  to  an  effective   registration
statement,  Purchaser  represents  that it is purchasing  the Shares for its own
account as principal for investment  purposes.  Purchaser  understands  that its
acquisition  of the Shares has not been  registered  under the Securities Act or
registered or qualified  under any State  securities law in reliance on specific
exemptions therefrom,  which exemptions may depend upon, among other things, the
bona fide nature of Purchaser's investment intent as expressed herein. Purchaser
will not, directly or indirectly, offer, sell, pledge, transfer,  hypothecate or
otherwise  dispose of (or  solicit  any offers to buy,  purchaser  or  otherwise
acquire  or take a pledge of) any of the Shares  except in  compliance  with the
Securities  Act and any  applicable  state  securities  laws,  and the rules and
regulations promulgated thereunder.

            4.4   Registration  or  Exemption  Requirements.  Purchaser  further
acknowledges and understands  that the Shares may not be transferred,  resold or
otherwise  disposed of except in a transaction  registered  under the Securities
Act and any applicable  State  securities  laws or unless an exemption from such
registration  is  available.   Purchaser  understands  that  the  certificate(s)
evidencing  the  Shares  will be  imprinted  with a legend  that  prohibits  the
transfer of the Shares unless (i) they are  registered or such  registration  is
not  required,  and  (ii) if the  transfer  is  pursuant  to an  exemption  from
registration  other than Rule 144 under the  Securities  Act and, if the Company
shall so request in writing,  an opinion of counsel  reasonably  satisfactory to
the Company is obtained to the effect that the transaction is so exempt.

            4.5   No Legal, Tax or Investment Advice. Purchaser understands that
nothing in this  Agreement  or any other  materials  presented  to  Purchaser in
connection with the purchase and sale of the Shares  constitutes  legal,  tax or
investment advice.  Purchaser has relied on, and has consulted with, such legal,
tax and investment advisors as it, in its sole discretion,  has deemed necessary
or appropriate in connection with its purchase of the Shares.

            4.6   Purchaser  Review.  Purchaser  hereby  represents and warrants
that  the  Purchaser  has  carefully  examined  the  Reports  and the  financial
statements  contained therein.  The Purchaser  acknowledges that the Company has
made  available to the  Purchaser  all  documents  and  information  that it has
requested  relating  to the  Company  and  has  provided  answers  to all of its
questions concerning the Company and the Shares.


                                       7




Nothing stated in the previous two sentences, however, shall be deemed to affect
the representations and warranties of the Company contained in this Agreement.

            4.7   Restrictions  on  Conversion  of Shares.  The Purchaser or any
subsequent  holder  of the  shares  (the  "Holder")  shall  be  prohibited  from
converting any portion of the Convertible  Preferred Stock which would result in
the  Purchaser or the Holder being deemed the  beneficial  owner,  in accordance
with the  provisions  of Rule 13d-3 of the Exchange Act, of 4.99% or more of the
then issued and outstanding Common Stock of the Company.

            Section 5. Conditions to the Purchaser's Obligation to Purchase. The
Company  understands that each Purchaser's  obligation to purchase the Shares is
conditioned upon:

            (a)   Acceptance by Purchaser of this  Agreement for the purchase of
the Shares,  as evidenced by the  execution of this  Agreement by an  authorized
officer;

            (b)   Delivery of the Shares into Escrow;

            (c)   Execution and delivery by the Company of the Escrow  Agreement
and the Registration Rights Agreement in the form of Attachment I and Attachment
11;

            (d)   Delivery of a filed Certificate of Designation; and

            (e)   Delivery of an Opinion of Counsel as per Section 3.17 herein.

            Section 6.  Conditions to Company's  Obligation to Sell.  Purchasers
understand that the Company's obligation to sell the Shares is conditioned upon:

            (a)   The receipt and  acceptance  by the Company of this  Agreement
for  all of the  Shares  as  evidenced  by  execution  of this  Agreement  by an
authorized officer.

            (b)   Delivery into escrow by Purchasers of good funds as payment in
full for the purchase of the Shares; and

            (c)   Execution  and  delivery  by  the  Purchasers  of  the  Escrow
Agreement and the Registration Rights Agreement in the forms of Attachment I and
Attachment II.

            Section 7. Compliance with the Securities Act.

            7.1   Registration  Rights Agreement.  The parties will enter into a
Registration Rights Agreement, annexed hereto as Attachment II.

            7.2   Underwriter.  The  Company  understands  that  the  Purchasers
disclaim  being an  "underwriter"  (as such term is defined under the Securities
Act and the rules and regulations  promulgated  thereunder (an  "Underwriter")),
but Purchasers being deemed an Underwriter  shall not relieve the Company of any
obligation it has hereunder, except as may be required by law.




                                       8






            7.3   Indemnification.  Each of the Company and the Purchasers agree
to indemnify  the other and to hold the other  harmless from and against any and
all losses,  damages,  liabilities,  costs and  expenses  (including  reasonable
attorneys'  fees)  which the other may sustain or incur in  connection  with the
breach by the  indemnifying  party of any  representation,  warranty or covenant
made by it in this Agreement.

            7.4   Information  Available.  So long as any registration statement
is effective covering the resale of the Common Shares and the Conversion Shares,
the Company will furnish to Purchasers :

            (a)   as soon as possible  after  available  (but in the case of the
Company's Annual Report to  Stockholders,  within 150 days after the end of each
fiscal year of the Company),  one copy of (i) its Annual Report to  Stockholders
(which Annual report shall contain  financial  statements  audited in accordance
with generally accepted accounting principles in the United States of America by
a national  firm of certified  public  accountants);  (ii) each of its Quarterly
Reports to Stockholders,  and its Quarterly Reports on Form 10-QSB;  and (iii) a
full copy of the  registration  statement  covering the  Conversion  Shares (the
foregoing, in each case, including exhibits); and

            (b)   upon  the  reasonable  request  of  Purchasers  ,  such  other
information that is generally available to the public.

            7.5   Temporary  Cessation  of Offers and Sales by  Purchasers . The
Purchasers acknowledge that there may occasionally be times when the Company may
be  required  to  suspend  the  use  of  the  prospectus  forming  part  of  the
Registration  Statement  until  such time as an  amendment  to the  Registration
Statement  has  been  filed  by  the  Company  and  declared  effective  by  the
Commission,  until the prospectus is  supplemented or amended to comply with the
Securities  Act,  or until  such time as the  Company  has filed an  appropriate
report with the  Commission  pursuant to the Exchange Act. The Company agrees to
file any necessary  amendments,  supplements  and reports as soon as practicable
under the  circumstances.  Purchasers  hereby covenant that it will not sell any
Common  Stock  pursuant to said  prospectus  during a period of not more than 45
days commencing at the time at which the Company gives the Purchasers  notice of
the suspension of the use of said  prospectus and ending at the time the Company
gives the Purchasers  notice that the  Purchasers  may  thereafter  effect sales
pursuant to said prospectus, as the same may have been supplemented or amended.

            7.6   Transfer of Common Stock After Registration. Purchasers hereby
covenant with the Company not to make any sale of the Common Stock except either
(i) in accordance  with the  Registration  Statement,  in which case  Purchasers
covenant to comply with the requirement of delivering a current  prospectus,  or
(ii) such time as all of the Common Stock may be sold in any three-month  period
pursuant to Rule 144 under the Securities Act.

            7.7   Termination  of  Obligations.  The  obligations of the Company
pursuant to the Registration Rights Agreement shall cease and terminate upon the
earlier to occur of (i) such time as,  all of the  Conversion  Shares  have been
sold by  Purchasers , or (ii) such time as all of the  Conversion  Shares may be
sold in any three month period pursuant to Rule 144 under the Securities Act.

            7.8   Legend.  The  certificate  or  certificates  representing  the
Shares and, upon conversion,  the Conversion Shares shall be subject to a legend
restricting  transfer  under  the  Securities  Act of 1933,  such  legend  to be
substantially as follows:


                                       9




"THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933,  AS AMENDED (THE "ACT").  THESE  SECURITIES  HAVE BEEN ACQUIRED FOR
INVESTMENT,  AND MAY NOT BE TRANSFERRED OR DISPOSED OF UNLESS (1) A REGISTRATION
STATEMENT  UNDER THE ACT IS THEN IN EFFECT WITH RESPECT THERETO AND SUCH SALE IS
MADE  PURSUANT TO SUCH  REGISTRATION  STATEMENT  OR (2) A WRITTEN  OPINION  FROM
COUNSEL  REASONABLY  SATISFACTORY  TO THE COMPANY IS OBTAINED TO THE EFFECT THAT
SUCH  TRANSFER  OR  DISPOSITION  WILL  NOT  VIOLATE  THE ACT AND THE  RULES  AND
REGULATIONS PROMULGATED THEREUNDER."

            Such  securities  shall also  include  any  legends  required by any
applicable state securities laws.

            With respect to the Shares and the Conversion  Shares, the legend(s)
shall be removed and the Company shall issue a replacement  certificate  without
such legend to the holder of such  certificate  if such  holder  provides to the
Company an  opinion of counsel  reasonably  acceptable  to the  Company,  to the
effect  that a sale,  transfer  or  assignment  of such  securities  may be made
without registration.

            7.10  Permissive Redemption. The Company has the right to redeem the
Convertible Preferred Stock, in whole or in part, in cash or in Common Stock, as
follows:

            When a conversion request is submitted and when the Conversion Price
is below  $3.40,  the  Company  has the option to redeem all or a portion of the
outstanding  Convertible  Preferred Stock for a redemption  price equal to $3.40
multiplied by the number of shares the Convertible Preferred Stock would convert
into on the date of redemption (the "Redemption Price").

            The Company shall give written  notice by telecopy to the Purchasers
of its election to redeem the  Convertible  Preferred Stock one (1) business day
after  receipt of the Notice of  Conversion.  Upon notice of its right to redeem
the Convertible  Preferred Stock the Company shall wire transfer the appropriate
amount of funds which shall include  Redemption Price, as defined in Certificate
of  Designation  filed May 15, 1998,  and any and all penalties  and  liquidated
damages,  if any,  to  Purchasers  within ten (10) days of such  notice.  If the
Company  does not wire the  appropriate  amounts  of funds to  Purchasers  , the
Company shall pay to the  Purchasers a penalty in an amount in cash equal to two
(2%)  percent of the  Redemption  Price to be paid for such  redemption.  If the
Company fails to pay the Redemption  Price on the Redemption Date, as defined in
the Certificate of Designation filed May 15, 1998, the Purchasers shall have the
right to convert the  Convertible  Preferred Stock  previously  presented to the
Company  and not  redeemed.  The  Company  shall  have the right to  redeem  the
Convertible  Preferred  Stock in accordance  with the terms of this paragraph in
any subsequent redemption;  provided,  however, that if the Company fails to pay
the  Redemption  Price in a  subsequent  redemption  within ten (10)  days,  the
Company  shall  have  the  right  to  redeem  the  Convertible  Preferred  Stock
thereafter,  only upon wiring the Redemption Price to the holders simultaneously
with sending the notice of  redemption.  On or after the  Redemption  Date,  the
holders of Convertible Preferred Stock called for redemption shall surrender the
certificates  evidencing  the shares called for redemption to the Company at the
place  designated  in such  notice and shall  thereupon  be  entitled to receive
payment of the Redemption Price.

            Section 8. Legal Fees and  Expenses.  Each of the parties  shall pay
its own fees and expenses  (including  the fees of any  attorneys,  accountants,
appraisers or others  engaged by such party) in connection  with this  Agreement
and the transactions contemplated hereby.




                                       10




            Section 9. Conversion. Conversion of the Convertible Preferred Stock
may be made at the Conversion Price as follows:

            No shares  of Series C  Preferred  Stock may be  converted  prior to
August 15, 1998. At any time after August 15, 1998 through November 14, 1998, up
to twenty-five  (25%) percent of the shares of Convertible  Preferred Stock then
outstanding  may  be  converted,  at the  option  of the  holders  thereof,  and
thereafter  on  November  15,  1998,  February  15,  1999 and May 15,  1999,  an
additional  twenty-five  (25%)  percent of the shares of  Convertible  Preferred
Stock then outstanding may be converted,  on a cumulative and pro rata basis, at
the  option of the  holders  thereof.  The  number  of shares of fully  paid and
nonassessable Common Stock into which each share of Convertible  Preferred Stock
may be converted shall be determined by dividing the  Liquidation  Preference by
the Conversion Price in effect on the Conversion Date.

            9.1   Notice of Conversion.  Purchasers may convert,  in whole or in
part,  the  Convertible  Preferred  Stock into Common  Stock by  telecopying  an
executed and  completed  Notice of  Conversion  (in the form  annexed  hereto as
Exhibit A) to the Company and delivering  the original  Notice of Conversion and
the certificate  representing the Convertible  Preferred Stock to the Company by
express courier within five (5) business days of exercise.  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 Common Stock issuable upon conversion
of all or any  part  of the  Convertible  Preferred  Stock  (together  with  the
certificates  representing  portions of the  Convertible  Preferred Stock not so
converted) to the Purchasers  via express  courier within five (5) business days
after the Company has  received  the original  Notice of  Conversion  and shares
certificate  being so  converted.  The  Notice  of  Conversion  and  certificate
representing  the portion of the Convertible  Preferred Stock converted shall be
delivered as follows and become  effective  upon delivery to each of the persons
below:

            To the Company:

            Xybernaut Corporation

            12701 Four Lakes Circle

            Fairfax, VA 22033

            Attn:     Edward G. Newman, President

            (Tele) (703) 631-6925

            (Fax) (703) 631-7070



            with copies to:



            Xybernaut Corporation

         

                                       11






            12701 Four Lakes Circle
 
            Fairfax, VA 22033
 
            Attn:     John Moynahan, Treasurer
 
            (tele) (703) 631-6925
 
            (fax) (703) 631-3903
 
 
 
            Steven A. Newman
 
            303 Avenida Cerritos
 
            Newport Beach, CA 92660
 
            (tele) (714) 760-5470
 
            (fax) (714) 760-3865
 
 
 
            Martin Eric Weisberg, Esq.
 
            Parker Chapin Flattau & Klimpl, LLP
 
            1211 Avenue of the Americas
 
            New York, NY 10019
 
            (tele) (212) 704-6000
 
            (fax) (212) 704-6288
 
 
 
            Christopher Auguste, Esq.
 
            Parker Chapin Flattau & Klimpl, LLP
 
            1211 Avenue of the Americas
 
            New York, NY 10019
 
            (tele) (212) 704-6000

 

                                       12






            (fax) (212) 704-6288

or to such other  person at such other place as the Company  shall  designate to
the Purchasers in writing.

            In the event that the  Convertible  Preferred Stock is not converted
within ten (10)  business  days of receipt by the  Company of a valid  Notice of
Conversion and certificates  representing the Convertible  Preferred Stock to be
converted  (such date of receipt  referred  to as the  "Conversion  Date"),  the
Company shall pay to the  Purchasers , by wire transfer,  as liquidated  damages
for such  failure  and not as a  penalty,  an amount  in cash  equal to one (1%)
percent per day of the purchase price of the  Convertible  Preferred Stock to be
converted which shall run from the initial Conversion Date and Purchaser has the
option to withdraw the Notice of Conversion previously sent; provided,  that the
Company  shall not be  responsible  for (or  required  to pay)  such  liquidated
damages if such failure to convert was not caused by any actions or omissions of
the Company.

            Section 10. [Intentionally blank]

            Section 11.  Notices.  All  notices,  requests,  consents  and other
communications  hereunder  shall be in  writing,  shall be mailed by first class
registered or certified airmail, postage prepaid, and shall be deemed given when
so mailed:

            (a)   if to the Company, to

                  Xybernaut Corporation

                  12701 Four Lakes Circle

                  Fairfax, VA 22033

                  Attn:     Edward G. Newman, President

                  (Tele) (703) 631-6925

                  (Fax) (703) 631-7070



            copy to:



                  Martin Eric Weisberg, Esq.

                  Parker Chapin Flattau & Klimpl, LLP

                  1211 Avenue of the Americas

                  New York, NY 10036


                                       13




                  (Tele) (212) 704-6050

                  (Fax) (212) 704-6288

or to such other  person at such other place as the Company  shall  designate to
the Purchasers in writing;

            (b)   if to the Purchasers , to

            Libertyview Plus Fund

            c/o Libertyview Capital Management

            101 Hudson Street

            Suite #3700

            Jersey City, New Jersey 07302

            (tele) 201-200-9093

            (fax) 201-200-1140

            copy to:

            Sheldon E. Goldstein, P.C.

            65 Broadway, 10th Fl.

            New York, NY 10006

            Attn:     Sheldon E. Goldstein

            (tele) (212) 809-4220

            (fax) (212) 809-4228

or at such other address or addresses as may have been  furnished to the Company
in writing; or

            (c)   if to any transferee or  transferees  of a Purchaser,  at such
address or addresses as shall have been  furnished to the Company at the time of
the  transfer or  transfers,  or at such other  address or addresses as may have
been furnished by such transferee or transferees to the Company in writing.

            Section 12.  Miscellaneous.

            12.1  Entire Agreement. This Agreement embodies the entire agreement
and understanding  between the parties hereto with respect to the subject matter
hereof and  supersedes all prior oral or written  agreements and  understandings
relating to the subject matter hereof. No statement, representation, warranty,



                                       14






covenant or  agreement  or any kind not  expressly  set forth in this  Agreement
shall affect, or be used to interpret, change or restrict, the express terms and
provisions of this Agreement.

            12.2  Amendments.  This  Agreement  may not be  modified  or amended
except  pursuant to an  instrument  in writing  signed by the Company and by the
Purchasers.

            12.3  Headings.  The  headings  of  the  various  sections  of  this
Agreement have been inserted for  convenience of reference only and shall not be
deemed to be part of this Agreement.

            12.4  Severability.   In  case  any  provision   contained  in  this
Agreement  should be  invalid,  illegal or  unenforceable  in any  respect,  the
validity,  legality and  enforceability  of the remaining  provisions  contained
herein shall not in any way be affected or impaired thereby.

            12.5  Governing  Law/Jurisdiction.  This Agreement will be construed
and  enforced in  accordance  with and  governed by the laws of the State of New
York,  except for matters arising under the Securities Act, without reference to
principles of conflicts of law. Each of the parties consents to the jurisdiction
of the courts of or located in the State of New York,  specifically the Southern
District  of New York  and/or  the  Supreme  Court  of the  State 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.  Each party hereby agrees that if another party to this Agreement
obtains a judgment  against it in such a  proceeding,  the party which  obtained
such judgment may enforce same by summary  judgment in the courts of any country
having jurisdiction over the party against whom such judgment was obtained,  and
each party hereby waives any defenses available to it under local law and agrees
to the enforcement of such a judgment.  Each party to this Agreement irrevocably
consents  to the  service of process in any such  proceeding  by the  mailing of
copies thereof by registered or certified mail,  postage prepaid,  to such party
at its address set forth  herein.  Nothing  herein shall affect the right of any
party to serve process in any other manner permitted by law.

            12.6  Certificate of Designation.  In the event of any inconsistency
or conflict between the terms and provisions of this Agreement and the terms and
provisions of the  Certificate of  Designation,  the terms and provisions of the
Certificate of Designation shall control.

            12.7  Recovery of Attorney's Fees.  Should any party bring an action
to enforce  the terms of this  Agreement  then,  if  Purchasers  prevail in such
action  it  should be  entitled  to  recovery  of its  attorney's  fees from the
Company,  and if the  Company  prevails  in such  action it shall be entitled to
recovery of its attorney's fees from the Purchasers .

            12.8  Fees.  Notwithstanding  Section 12.7, the Company acknowledges
that Purchasers shall have no responsibility  for the payment of any of its fees
in connection with this offering.

            12.9  Counterparts/Facsimile.  This Agreement may be executed in two
or more  counterparts,  each of which shall  constitute an original,  but all of
which,  when taken  together,  shall  constitute but one  instrument,  and shall
become  effective when one or more  counterparts  have been signed by each party
hereto and delivered to the other party.  In lieu of the  original,  a facsimile
transmission  or copy of the original  shall be as effective and  enforceable as
the original.

            12.10 Publicity.  The Purchasers  shall not issue any press releases
or  otherwise  make  any  public  statement  with  respect  to the  transactions
contemplated by this Agreement without the prior written consent of the Company,
except as may be required by applicable law or regulation.



                                       15




            12.11 Survival. The representations and warranties in this Agreement
shall survive Closing.

            IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be signed by their duly authorized  representatives the day and year first above
written.

                                               XYBERNAUT CORPORATION



                                               By ____________________________
                                                  Officer



                                               LIBERTYVIEW PLUS FUND, Purchaser



                                               By ____________________________
                                                  Officer



                                               LIBERTYVIEW FUND, LLC, Purchaser



                                               By ____________________________
                                                  Officer



                                               CPR (USA) INC., Purchaser



                                               By ____________________________
                                                  Officer


                                       16




                                                                       EXHIBIT A

                              NOTICE OF CONVERSION

        (To be Executed by the Registered Holder in order to Convert the

                    5% Series C Convertible Preferred Stock)

            The undersigned  hereby  irrevocably  elects to convert shares of 5%
Convertible Preferred Stock, Certificate No. (the "Preferred Stock") into shares
of common  stock of  Xybernaut  Corporation  (the  "Company")  according  to the
conditions hereof, as of the date written below.

            The undersigned represents and warrants that

            (i)   All  offers  and  sales by the  undersigned  of the  shares of
Common Stock issuable to the undersigned  upon conversion of the Preferred Stock
shall be made in compliance  with  Regulation  D, pursuant to an exemption  from
registration  under the  Securities  Act of 1933,  as amended  (the  "Securities
Act"), or pursuant to registration of the Common Stock under the Act, subject to
any  restrictions  on sale or transfer set forth in the Preferred Stock Purchase
Agreement  between  the  Company  and the  original  holder  of the  Certificate
submitted herewith for conversion.

            (ii)  Upon  conversion  pursuant to this Notice of  Conversion,  the
undersigned  will not own or deemed to  beneficially  own (within the meaning of
the  Securities  Exchange  Act of 1934,  as  amended)  4.99% or more of the then
issued and outstanding shares of the company.




_________________________                            ___________________________
Date of Conversion                                   Applicable Conversion Price



_________________________                            ___________________________
Number of Common Shares upon                         $ Amount of Conversion

Conversion


_________________________                            ___________________________
Signature                                                      Name

Address:                                             Delivery of Shares to:





                                       17