<PAGE>

                                                                 Exhibit 4.3

                                                           Execution Version


                                  EXHIBIT C
                                  ---------

NEITHER THESE SECURITIES NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE
EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION
OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES
ACT"), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN
AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH
APPLICABLE STATE SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL
TO THE TRANSFEROR TO SUCH EFFECT, THE SUBSTANCE OF WHICH SHALL BE REASONABLY
ACCEPTABLE TO THE COMPANY. THESE SECURITIES AND THE SECURITIES ISSUABLE UPON
EXERCISE OF THESE SECURITIES MAY BE PLEDGED IN A MANNER CONSISTENT WITH THE
SECURITIES ACT IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT SECURED BY SUCH
SECURITIES.

                           ZOLTEK COMPANIES, INC.



                                   WARRANT

Warrant No. [ ]               Date of Original Issuance: February 9, 2005

         Zoltek Companies, Inc., a Missouri corporation (the "COMPANY"),
hereby certifies that, for value received, [ ] or its registered assigns
(the "HOLDER"), is entitled to purchase from the Company up to a total of
[ ](1) shares of common stock, par value $0.01 per share (the "COMMON STOCK"),
of the Company (each such share, a "WARRANT SHARE" and all such shares, the
"WARRANT SHARES") at an exercise price equal to $17.50 per share (as
adjusted from time to time as provided in Section 9, the "EXERCISE PRICE"),
at any time and from time to time from and after the date hereof and through
and including February 9, 2009 (the "EXPIRATION DATE"), and subject to
the following terms and conditions:

         1. Definitions. In addition to the terms defined elsewhere in this
            -----------
Warrant, capitalized terms that are not otherwise defined herein shall have the
meanings given to such terms in the Loan and Warrant Agreement, dated as of
February [ ], 2005 to which the Company and the original Holder are parties
(the "PURCHASE AGREEMENT").

<FN>
--------
(1) 40% warrant coverage based on the amount of the Holder's pro rata
    percentage of the Notes divided by the Exercise Price.



         2.  Registration of Warrant. The Company shall register this
             -----------------------
Warrant, upon records to be maintained by the Company for that purpose (the
"WARRANT REGISTER"), in the name of the record Holder hereof from time to
time. The Company may deem and treat the registered Holder of this Warrant
as the absolute owner hereof for the purpose of any exercise hereof or any
distribution to the Holder, and for all other purposes, absent actual notice
to the contrary.

         3.  Registration of Transfers. The Company shall register the
             -------------------------
transfer of any portion of this Warrant in the Warrant Register, upon
surrender of this Warrant, with the Form of Assignment attached hereto duly
completed and signed, to the Company at its address specified herein. Upon
any such registration or transfer, a new Warrant to purchase Common Stock,
in substantially the form of this Warrant (any such new Warrant, a "NEW
WARRANT"), evidencing the portion of this Warrant so transferred shall be
issued to the transferee and a New Warrant evidencing the remaining portion
of this Warrant not so transferred, if any, shall be issued to the
transferring Holder. The acceptance of the New Warrant by the transferee
thereof shall be deemed the acceptance by such transferee of all of the
rights and obligations of a holder of a Warrant.

         4.  Exercise and Duration of Warrants. This Warrant shall be
             ---------------------------------
exercisable by the registered Holder at any time and from time to time on or
after the date hereof to and including the Expiration Date. At 6:30 p.m.,
New York City time on the Expiration Date, the portion of this Warrant not
exercised prior thereto shall be and become void and of no value, provided,
                                                                  --------
that if the closing sales price of the Common Stock on the Expiration Date
is greater than 102% of the Exercise Price on the Expiration Date, then this
Warrant shall be deemed to have been exercised in full (to the extent not
previously exercised) on a "cashless exercise" basis at 6:30 P.M. New York
City time on the Expiration Date. The Company may not call or redeem all or
any portion of this Warrant without the prior written consent of the Holder.

         5.  Delivery of Warrant Shares.
             --------------------------

             (a)  To effect exercises hereunder, the Holder shall not be
required to physically surrender this Warrant unless the aggregate Warrant
Shares represented by this Warrant is being exercised. Upon delivery of the
Exercise Notice to the Company (with the attached Warrant Shares Exercise
Log) at its address for notice set forth herein and upon payment of the
Exercise Price multiplied by the number of Warrant Shares that the Holder
intends to purchase hereunder, the Company shall promptly (but in no event
later than three Trading Days after the Date of Exercise (as defined
herein)) issue and deliver to the Holder, a certificate for the Warrant
Shares issuable upon such exercise, which, unless otherwise required by the
Purchase Agreement, shall be free of restrictive legends. The Company shall,
upon request of the Holder and subsequent to the date on which a
registration statement covering the resale of the Warrant Shares has been
declared effective by the Securities and Exchange Commission, use its best
efforts to deliver Warrant Shares hereunder electronically through The
Depository Trust Corporation or another established clearing corporation
performing similar functions, if available, provided, that, the Company may,
but will not be required to change its transfer agent if its current
transfer agent cannot deliver Warrant Shares electronically through the
Depository Trust Corporation. A "DATE OF EXERCISE" means the date on which
the Holder shall have delivered to Company: (i) the Exercise Notice (with
the Warrant Exercise Log attached to it), appropriately completed and duly
signed and (ii) if such Holder is not utilizing the

                                     2


cashless exercise provisions set forth in this Warrant, payment of the
Exercise Price for the number of Warrant Shares so indicated by the Holder
to be purchased.

             (b)  If by the third Trading Day after a Date of Exercise the
Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), then the Holder will have the right to
rescind such exercise.

             (c)  If by the third Trading Day after a Date of Exercise the
Company fails to deliver the required number of Warrant Shares in the manner
required pursuant to Section 5(a), and if after such third Trading Day and
prior to the receipt of such Warrant Shares, the Holder purchases (in an
open market transaction or otherwise) shares of Common Stock to deliver in
satisfaction of a sale by the Holder of the Warrant Shares which the Holder
anticipated receiving upon such exercise (a "BUY-IN"), then the Company
shall (1) pay in cash to the Holder the amount by which (x) the Holder's
total purchase price (including brokerage commissions, if any) for the
shares of Common Stock so purchased exceeds (y) the amount obtained by
multiplying (A) the number of Warrant Shares that the Company was required
to deliver to the Holder in connection with the exercise at issue by (B) the
closing bid price of the Common Stock at the time of the obligation giving
rise to such purchase obligation and (2) at the option of the Holder, either
reinstate the portion of the Warrant and equivalent number of Warrant Shares
for which such exercise was not honored or deliver to the Holder the number
of shares of Common Stock that would have been issued had the Company timely
complied with its exercise and delivery obligations hereunder. The Holder
shall provide the Company written notice indicating the amounts payable to
the Holder in respect of the Buy-In.

             (d)  The Company's obligations to issue and deliver Warrant
Shares in accordance with the terms hereof are absolute and unconditional,
irrespective of any action or inaction by the Holder to enforce the same,
any waiver or consent with respect to any provision hereof, the recovery of
any judgment against any Person or any action to enforce the same, or any
setoff, counterclaim, recoupment, limitation or termination, or any breach
or alleged breach by the Holder or any other Person of any obligation to the
Company or any violation or alleged violation of law by the Holder or any
other Person, and irrespective of any other circumstance which might
otherwise limit such obligation of the Company to the Holder in connection
with the issuance of Warrant Shares. Nothing herein shall limit a Holder's
right to pursue any other remedies available to it hereunder, at law or in
equity including, without limitation, a decree of specific performance
and/or injunctive relief with respect to the Company's failure to timely
deliver certificates representing shares of Common Stock upon exercise of
the Warrant as required pursuant to the terms hereof.

         6.  Charges, Taxes and Expenses. Issuance and delivery of
             ---------------------------
certificates for shares of Common Stock upon exercise of this Warrant shall
be made without charge to the Holder for any issue or transfer tax,
withholding tax, transfer agent fee or other incidental tax or expense in
respect of the issuance of such certificates, all of which taxes and
expenses shall be paid by the Company; provided, however, that the Company
shall not be required to pay any tax which may be payable in respect of any
transfer involved in the registration of any certificates for Warrant Shares
or Warrants in a name other than that of the Holder. The Holder shall be
responsible for all other tax liability that may arise as a result of
holding or transferring this Warrant or receiving Warrant Shares upon
exercise hereof.

                                     3


         7.  Replacement of Warrant. If this Warrant is mutilated, lost,
             ----------------------
stolen or destroyed, the Company shall issue or cause to be issued in
exchange and substitution for and upon cancellation hereof, or in lieu of
and substitution for this Warrant, a New Warrant, but only upon receipt of
evidence reasonably satisfactory to the Company of such loss, theft or
destruction and customary and reasonable indemnity (which may include a
surety bond for any Holder other than the original Holder of the Warrant),
if requested. Applicants for a New Warrant under such circumstances shall
also comply with such other reasonable regulations and procedures and pay
such other reasonable third-party costs as the Company may prescribe. If a
New Warrant is requested as a result of a mutilation of this Warrant, then
the Holder shall deliver such mutilated Warrant to the Company as a
condition precedent to the Company's obligation to issue the New Warrant.

         8.  Reservation of Warrant Shares. The Company covenants that it
             -----------------------------
will at all times reserve and keep available out of the aggregate of its
authorized but unissued and otherwise unreserved Common Stock, solely for
the purpose of enabling it to issue Warrant Shares upon exercise of this
Warrant as herein provided, the number of Warrant Shares which are then
issuable and deliverable upon the exercise of this entire Warrant, free from
preemptive rights or any other contingent purchase rights of persons other
than the Holder (taking into account the adjustments and restrictions of
Section 9). The Company covenants that all Warrant Shares so issuable and
---------
deliverable shall, upon issuance and the payment of the applicable Exercise
Price in accordance with the terms hereof, be duly and validly authorized,
issued and fully paid and nonassessable.

         9.  Certain Adjustments. The Exercise Price and number of Warrant
             -------------------
Shares issuable upon exercise of this Warrant are subject to adjustment from
time to time as set forth in this Section 9.
                                  ---------

             (a)  Stock Dividends and Splits. If the Company, at any time
                  --------------------------
while this Warrant is outstanding, (i) pays a stock dividend on its Common
Stock or otherwise makes a distribution on any class of capital stock that
is payable in shares of Common Stock, (ii) subdivides outstanding shares of
Common Stock into a larger number of shares, or (iii) combines outstanding
shares of Common Stock into a smaller number of shares, then in each such
case the Exercise Price shall be multiplied by a fraction of which the
numerator shall be the number of shares of Common Stock outstanding
immediately before such event and of which the denominator shall be the
number of shares of Common Stock outstanding immediately after such event.
Any adjustment made pursuant to clause (i) of this paragraph shall become
effective immediately after the record date for the determination of
shareholders entitled to receive such dividend or distribution, and any
adjustment pursuant to clause (ii) or (iii) of this paragraph shall become
effective immediately after the effective date of such subdivision or
combination. If any event requiring an adjustment under this paragraph
occurs during the period that an Exercise Price is calculated hereunder,
then the calculation of such Exercise Price shall be adjusted appropriately
to reflect such event.

             (b)  Pro Rata Distributions. If the Company, at any time while
                  ----------------------
this Warrant is outstanding, distributes to all holders of Common Stock (i)
evidences of its indebtedness, (ii) any security (other than a distribution
of Common Stock covered by the preceding paragraph), (iii) rights or
warrants to subscribe for or purchase any security, or (iv) any other asset
(in each case, "DISTRIBUTED PROPERTY"), then, at the request of any Holder
delivered before the 90th day

                                     4


after the record date fixed for determination of shareholders entitled to
receive such distribution, the Company will deliver to such Holder, within
five Trading Days after such request (or, if later, on the effective date of
such distribution), the Distributed Property that such Holder would have
been entitled to receive in respect of the Warrant Shares for which such
Holder's Warrant could have been exercised immediately prior to such record
date. If such Distributed Property is not delivered to a Holder pursuant to
the preceding sentence, then upon any exercise of the Warrant that occurs
after such record date, such Holder shall be entitled to receive, in
addition to the Warrant Shares otherwise issuable upon such conversion, the
Distributed Property that such Holder would have been entitled to receive in
respect of such number of Warrant Shares had the Holder been the record
holder of such Warrant Shares immediately prior to such record date.
Notwithstanding the foregoing, this Section 9(b) shall not apply to any
distribution of rights or securities in respect of adoption by the Company
of a shareholder rights plan which events shall be covered by the
anti-dilution provisions of Section 9(a).

             (c)  Fundamental Transactions. If, at any time while this
                  ------------------------
Warrant is outstanding, (1) the Company effects any merger or consolidation
of the Company with or into another Person, (2) the Company effects any sale
of all or substantially all of its assets in one or a series of related
transactions, (3) any tender offer or exchange offer approved or authorized
by the Board of Directors of the Company (whether by the Company or another
Person) is completed pursuant to which holders of Common Stock are permitted
to tender or exchange their shares for other securities, cash or property,
or (4) the Company effects any reclassification of the Common Stock or any
compulsory share exchange pursuant to which the Common Stock is effectively
converted into or exchanged for other securities, cash or property (in any
such case, a "FUNDAMENTAL TRANSACTION"), then the Holder shall have the
right thereafter to receive, upon exercise of this Warrant, the same amount
and kind of securities, cash or property as it would have been entitled to
receive upon the occurrence of such Fundamental Transaction if it had been,
immediately prior to such Fundamental Transaction, the holder of the number
of Warrant Shares then issuable upon exercise in full of this Warrant (the
"ALTERNATE CONSIDERATION"). For purposes of any such exercise, the
determination of the Exercise Price shall be appropriately adjusted to apply
to such Alternate Consideration based on the amount of Alternate
Consideration issuable in respect of one share of Common Stock in such
Fundamental Transaction, and the Company shall apportion the Exercise Price
among the Alternate Consideration in a reasonable manner reflecting the
relative value of any different components of the Alternate Consideration.
If holders of Common Stock are given any choice as to the securities, cash
or property to be received in a Fundamental Transaction, then the Holder
shall be given the same choice as to the Alternate Consideration it receives
upon any exercise of this Warrant following such Fundamental Transaction. At
the Holder's option and request, any successor to the Company or surviving
entity in such Fundamental Transaction shall, either (1) issue to the Holder
a new warrant substantially in the form of this Warrant and consistent with
the foregoing provisions and evidencing the Holder's right to purchase the
Alternate Consideration for the aggregate Exercise Price upon exercise
thereof, or (2) purchase the Warrant from the Holder for a purchase price,
payable in cash within five Trading Days after such request (or, if later,
on the effective date of the Fundamental Transaction), equal to the Black
Scholes value of the remaining unexercised portion of this Warrant on the
date of such request as well as assumptions reasonably mutually acceptable
to the Company and the Holder, provided, that for purposes of such
                               --------
calculation, the market price of the Common Stock shall be the closing bid
price of the Common Stock on the Trading Day immediately preceding the
public announcement of the Fundamental Transaction and the volatility factor
shall be

                                     5


determined by reference to the 12 month average industry volatility
measures. The terms of any agreement pursuant to which a Fundamental
Transaction is effected shall include terms requiring any such successor or
surviving entity to comply with the provisions of this paragraph (c) and
insuring that the Warrant (or any such replacement security) will be
similarly adjusted upon any subsequent transaction analogous to a
Fundamental Transaction.

             (d)  Subsequent Equity Sales.
                  -----------------------

                  (i)  While any portion of this Warrant is outstanding,
if the Company issues any shares of Common Stock or the Company or any
subsidiary thereof issues any rights, warrants, options or other securities
or debt that is convertible into, exchangeable for (any such securities,
"COMMON STOCK EQUIVALENTS") entitling any Person to acquire shares of Common
Stock, at a price per share less than the Exercise Price (if the holder of
the Common Stock or Common Stock Equivalent so issued shall at any time,
whether by operation of purchase price adjustments, reset provisions,
floating conversion, exercise or exchange prices or otherwise, or due to
warrants, options or rights issued in connection with such issuance, be
entitled to receive shares of Common Stock at a price less than the Exercise
Price, such issuance shall be deemed to have occurred for less than the
Exercise Price), then the Exercise Price shall be adjusted to equal the
conversion, exchange or purchase price for such Common Stock or Common Stock
Equivalents (including any reset provisions thereof) at issue and which
adjusted Exercise Price shall continue for as long as this Warrants remain
outstanding. Such adjustment shall be made whenever such Common Stock or
Common Stock Equivalents are issued. The Company shall notify the Holder in
writing, no later than the Trading Day following the issuance of any Common
Stock or Common Stock Equivalent subject to this section, indicating therein
the applicable issuance price, or of applicable reset price, exchange price,
conversion price and other pricing terms.

                  (ii) For purposes of this subsection 9(d), the following
subsections (d)(ii)(l) to (d)(ii)(6) shall also be applicable:

                       (1) Issuance of Rights or Options. In case at any time
                           -----------------------------
the Company shall in any manner grant (directly and not by assumption in a
merger or otherwise) any warrants or other rights to subscribe for or to
purchase, or any options for the purchase of, Common Stock or any stock or
security convertible into or exchangeable for Common Stock (such warrants,
rights or options being called "OPTIONS" and such convertible or
exchangeable stock or securities being called "CONVERTIBLE SECURITIES")
whether or not such Options or the right to convert or exchange any such
Convertible Securities are immediately exercisable, and the price per share
for which Common Stock is issuable upon the exercise of such Options or upon
the conversion or exchange of such Convertible Securities (determined by
dividing (i) the sum (which sum shall constitute the applicable
consideration) of (x) the total amount, if any, received or receivable by
the Company as consideration for the granting of such Options, plus (y) the
aggregate amount of additional consideration payable to the Company upon the
exercise of all such Options, plus (z), in the case of such Options which
relate to Convertible Securities, the aggregate amount of additional
consideration, if any, payable upon the issue or sale of such Convertible
Securities and upon the conversion or exchange thereof, by (ii) the total
maximum number of shares of Common Stock issuable upon the exercise of such
Options or upon the conversion or exchange of all such Convertible
Securities issuable upon the exercise of such

                                     6


Options) shall be less than the Exercise Price in effect immediately prior
to the time of the granting of such Options, then the total number of shares
of Common Stock issuable upon the exercise of such Options or upon
conversion or exchange of the total amount of such Convertible Securities
issuable upon the exercise of such Options shall be deemed to have been
issued for such price per share as of the date of granting of such Options
or the issuance of such Convertible Securities and thereafter shall be
deemed to be outstanding for purposes of adjusting the Exercise Price.
Except as otherwise provided in subsection 9(d)(ii)(3), no adjustment of the
Exercise Price shall be made upon the actual issue of such Common Stock or
of such Convertible Securities upon exercise of such Options or upon the
actual issue of such Common Stock upon conversion or exchange of such
Convertible Securities.

                       (2) Issuance of Convertible Securities. In case the
                           ----------------------------------
Company shall in any manner issue (directly and not by assumption in a
merger or otherwise) or sell any Convertible Securities, whether or not the
rights to exchange or convert any such Convertible Securities are
immediately exercisable, and the price per share for which Common Stock is
issuable upon such conversion or exchange (determined by dividing (i) the
sum (which sum shall constitute the applicable consideration) of (x) the
total amount received or receivable by the Company as consideration for the
issue or sale of such Convertible Securities, plus (y) the aggregate amount
of additional consideration, if any, payable to the Company upon the
conversion or exchange thereof, by (ii) the total number of shares of Common
Stock issuable upon the conversion or exchange of all such Convertible
Securities) shall be less than the Exercise Price in effect immediately
prior to the time of such issue or sale, then the total maximum number of
shares of Common Stock issuable upon conversion or exchange of all such
Convertible Securities shall be deemed to have been issued for such price
per share as of the date of the issue or sale of such Convertible Securities
and thereafter shall be deemed to be outstanding for purposes of adjusting
the Exercise Price, provided that (a) except as otherwise provided in
subsection 9(d)(ii)(3), no adjustment of the Exercise Price shall be made
upon the actual issuance of such Common Stock upon conversion or exchange of
such Convertible Securities and (b) no further adjustment of the Exercise
Price shall be made by reason of the issue or sale of Convertible Securities
upon exercise of any Options to purchase any such Convertible Securities for
which adjustments of the Exercise Price have been made pursuant to the other
provisions of subsection 9(d).

                       (3) Change in Option Price or Conversion Rate. Upon
                           -----------------------------------------
the happening of any of the following events, namely, if the purchase price
provided for in any Option referred to in subsection 9(d)(ii)(l) hereof, the
additional consideration, if any, payable upon the conversion or exchange of
any Convertible Securities referred to in subsections 9(d)(ii)(l) or
9(d)(ii)(2), or the rate at which Convertible Securities referred to in
subsections 9(d)(ii)(l) or 9(d)(ii)(2) are convertible into or exchangeable
for Common Stock shall change at any time (including, but not limited to,
changes under or by reason of provisions designed to protect against
dilution), the Exercise Price in effect at the time of such event shall
forthwith be readjusted to the Exercise Price which would have been in
effect at such time had such Options or Convertible Securities still
outstanding provided for such changed purchase price, additional
consideration or conversion rate, as the case may be, at the time initially
granted, issued or sold. On the termination of any Option for which any
adjustment was made pursuant to this subsection 9(d) or any right to convert
or exchange Convertible Securities for which any adjustment was

                                     7


made pursuant to this subsection 9(d) (including without limitation upon the
redemption or purchase for consideration of such Convertible Securities by
the Company), the Exercise Price then in effect hereunder shall forthwith be
changed to the Exercise Price which would have been in effect at the time of
such termination had such Option or Convertible Securities, to the extent
outstanding immediately prior to such termination, never been issued.

                       (4) Stock Dividends. Subject to the provisions of
                           ---------------
this Section 9(d), in case the Company shall declare a dividend or make any
other distribution upon any stock of the Company (other than the Common
Stock) payable in Common Stock, Options or Convertible Securities, then any
Common Stock, Options or Convertible Securities, as the case may be,
issuable in payment of such dividend or distribution shall be deemed to have
been issued or sold without consideration.

                       (5) Consideration for Stock. In case any shares of
                           -----------------------
Common Stock, Options or Convertible Securities shall be issued or sold for
cash, the consideration received therefor shall be deemed to be the net
amount received by the Company therefor, after deduction therefrom of any
expenses incurred or any underwriting commissions or concessions paid or
allowed by the Company in connection therewith. In case any shares of Common
Stock, Options or Convertible Securities shall be issued or sold for a
consideration other than cash, the amount of the consideration other than
cash received by the Company shall be deemed to be the fair value of such
consideration as determined in good faith by the Board of Directors of the
Company, after deduction of any expenses incurred or any underwriting
commissions or concessions paid or allowed by the Company in connection
therewith. In case any Options shall be issued in connection with the issue
and sale of other securities of the Company, together comprising one
integral transaction in which no specific consideration is allocated to such
Options by the parties thereto, such Options shall be deemed to have been
issued for such consideration as determined in good faith by the Board of
Directors of the Company. If Common Stock, Options or Convertible Securities
shall be issued or sold by the Company and, in connection therewith, other
Options or Convertible Securities (the "ADDITIONAL RIGHTS") are issued, then
the consideration received or deemed to be received by the Company shall be
reduced by the fair market value of the Additional Rights (as determined
using the Black-Scholes option pricing model or another method mutually
agreed to by the Company and the Holder). The Board of Directors of the
Company shall respond promptly, in writing, to an inquiry by the Holders as
to the fair market value of the Additional Rights. In the event that the
Board of Directors of the Company and the Holders are unable to agree upon
the fair market value of the Additional Rights, the Company and the Holders
shall jointly select an appraiser, who is experienced in such matters. The
decision of such appraiser shall be final and conclusive, and the cost of
such appraiser shall be borne evenly by the Company and the Holder.

                       (6) Record Date. In case the Company shall take a
                           -----------
record of the holders of its Common Stock for the purpose of entitling them
(i) to receive a dividend or other distribution payable in Common Stock,
Options or Convertible Securities or (ii) to subscribe for or purchase
Common Stock, Options or Convertible Securities, then such record date shall
be deemed to be the date of the issue or sale of the shares of Common Stock
deemed to have been issued or sold upon the declaration of such dividend or
the making of such other

                                     8


distribution or the date of the granting of such right of subscription or
purchase, as the case may be.

                  (iii) Notwithstanding the foregoing, no adjustment will
be made under this Section 9(d) as a result of: (i) the issuance of
securities upon the exercise or conversion of any Common Stock Equivalents
issued by the Company prior to the date of this Agreement (but will apply to
any amendments, modifications and reissuances thereof), (ii) the grant of
options or warrants, or the issuance of additional securities, under any
duly authorized company stock option, stock incentive plan, restricted stock
plan or stock purchase plan in existence on the Closing Date, (iii) the
issuance of Common Stock in payment of interest on the 2004 Notes, the 2003
Debentures, the 2004 Debentures or the Notes, or (iv) the issuance of Common
Stock Equivalents pursuant to a Strategic Transaction.

             (e)  Number of Warrant Shares. Simultaneously with any
                  ------------------------
adjustment to the Exercise Price pursuant to paragraph (a) of this Section,
the number of Warrant Shares that may be purchased upon exercise of this
Warrant shall be increased or decreased proportionately, so that after such
adjustment the aggregate Exercise Price payable hereunder for the adjusted
number of Warrant Shares shall be the same as the aggregate Exercise Price
in effect immediately prior to such adjustment.

             (f)  Calculations. All calculations under this Section 9 shall
                  ------------                              ---------
be made to the nearest cent or the nearest 1/100th of a share, as
applicable. The number of shares of Common Stock outstanding at any given
time shall not include shares owned or held by or for the account of the
Company, and the disposition of any such shares shall be considered an issue
or sale of Common Stock.

             (g)  Notice of Adjustments. Upon the occurrence of each
                  ---------------------
adjustment pursuant to this Section 9, the Company at its expense will
                            ---------
promptly compute such adjustment in accordance with the terms of this
Warrant and prepare a certificate setting forth such adjustment, including a
statement of the adjusted Exercise Price and adjusted number or type of
Warrant Shares or other securities issuable upon exercise of this Warrant
(as applicable), describing the transactions giving rise to such adjustments
and showing in detail the facts upon which such adjustment is based. Upon
written request, the Company will promptly deliver a copy of each such
certificate to the Holder and to the Company's transfer agent.

             (h)  Notice of Corporate Events. If the Company (i) declares a
                  --------------------------
dividend or any other distribution of cash, securities or other property in
respect of its Common Stock, including without limitation any granting of
rights or warrants to subscribe for or purchase any capital stock of the
Company or any Subsidiary, (ii) authorizes or approves, enters into any
agreement contemplating or solicits shareholder approval for any Fundamental
Transaction or (iii) authorizes the voluntary dissolution, liquidation or
winding up of the affairs of the Company, then the Company shall deliver to
the Holder a notice describing the material terms and conditions of such
transaction, at least 20 calendar days prior to the applicable record or
effective date on which a Person would need to hold Common Stock in order to
participate in or vote with respect to such transaction, and the Company
will take all steps reasonably necessary in order to insure that the Holder
is given the practical opportunity to exercise this Warrant prior to such
time so as to participate in or vote with respect to such transaction;
provided, however, that the

                                     9


failure to deliver such notice or any defect therein shall not affect the
validity of the corporate action required to be described in such notice.

         10. Payment of Exercise Price. The Holder may pay the Exercise Price
             -------------------------
in one of the following manners:

             (a)  Cash Exercise. The Holder may deliver immediately available
                  -------------
funds; or

             (b)  Cashless Exercise. The Holder may notify the Company in an
                  -----------------
Exercise Notice of its election to utilize cashless exercise, in which event
the Company shall issue to the Holder the number of Warrant Shares
determined as follows:

                           X = Y [(A-B)/A]

                  where:

                           X = the number of Warrant Shares to be issued to
                           the Holder.

                           Y = the number of Warrant Shares with
                           respect to which this Warrant is being
                           exercised.

                           A = the average of the closing prices
                           for the five Trading Days immediately
                           prior to (but not including) the
                           Exercise Date.

                           B = the Exercise Price.

For purposes of Rule 144 promulgated under the Securities Act, it is
intended, understood and acknowledged that the Warrant Shares issued in a
cashless exercise transaction shall be deemed to have been acquired by the
Holder, and the holding period for the Warrant Shares shall be deemed to
have commenced, on the date this Warrant was originally issued.

         11. Limitations on Exercise.
             -----------------------

                  (i)   Notwithstanding anything to the contrary contained
herein, the number of shares of Common Stock that may be acquired by a
Holder upon any exercise of Warrants (or otherwise in respect hereof) shall
be limited to the extent necessary to insure that, following such exercise
(or other issuance), the total number of shares of Common Stock then
beneficially owned by such Holder and its Affiliates and any other Persons
whose beneficial ownership of Common Stock would be aggregated with such
Holder's for purposes of Section 13(d) of the Exchange Act, does not exceed
4.999% (the "THRESHOLD PERCENTAGE") or 9.999% (the "MAXIMUM PERCENTAGE") of
the total number of issued and outstanding shares of Common Stock (including
for such purpose the shares of Common Stock issuable upon such conversion).
For such purposes, beneficial ownership shall be determined in accordance
with Section 13(d) of the Exchange Act and the rules and regulations
promulgated thereunder. Each delivery of an Exercise Notice hereunder will
constitute a representation by the Holder that it has evaluated the
limitation set forth in this paragraph and determined that issuance of the
full number of Warrant Shares requested in such Exercise Notice is permitted
under this paragraph. The Company's obligation to issue shares of Common
Stock in excess of the limitation referred to in this Section shall be
suspended (and shall not terminate or expire notwithstanding any contrary
provisions

                                     10


hereof) until such time, if any, as such shares of Common Stock may be
issued in compliance with such limitation, but in no event later than the
Expiration Date. By written notice to the Company, the Holder may waive the
provisions of this Section or increase or decrease the Maximum Percentage to
any other percentage specified in such notice, but (i) any such waiver or
increase will not be effective until the 61st day after such notice is
delivered to the Company, and (ii) any such waiver or increase or decrease
will apply only to the Holder and not to any other holder of Warrants.

                  (ii)  Notwithstanding anything to the contrary in this
Warrant, if the Company has not previously obtained Shareholder Approval (as
defined below), then the Company may not issue shares of Common Stock in
excess of the Issuable Maximum upon execerise of this Warrant at an exercise
price which is less than the Closing Price on the Trading Day immediately
preceding the Original Issue Date (the "THRESHOLD PRICE"). The "Issuable
Maximum" means, as of any date, a number of shares of Common Stock equal to
19.99% of the outstanding shares of Common Stock immediately preceding the
closing date of the transactions contemplated by the 2003 Securities
Purchase Agreement, less such number of shares of Common Stock as have been
issued at a price below the Threshold Price (1) upon exercise of the
Warrants and warrants issued under the 2003 Securities Purchase Agreement,
the 2004 Securities Purchase Agreement or the 2004 Loan Agreement, (2) upon
conversion of the 2003 Debentures, the 2004 Debentures and the 2004 Notes,
and (3) upon conversion of the Notes, or in payment of interest thereunder.
Each Holder shall be entitled to a portion of the Issuable Maximum equal to
the quotient obtained by dividing: (x) the principal amount of Notes issued
and sold to such Holder on the Original Issue Date by (y) the aggregate
principal amount of all Notes issued and sold by the Company on the Original
Issue Date. If any Holder shall no longer hold Notes, then such Holder's
remaining portion of the Issuable Maximum (other than those represented by
the remaining portion of this Warrant and the other warrants referenced in
clause (1) above) shall be allocated pro-rata among the remaining Holders,
giving effect to the Company's desire to allocate among the class of
securities known as the Notes this limitation. If on any Date of Exercise,
or at such time as a Holder shall notify the Company that the condition in
(A) following this clause shall be in effect: (A) the aggregate number of
shares of Common Stock that would then be issuable upon exercise in full of
this Warrant would exceed the Issuable Maximum on such date, and (B) the
Company shall not have previously obtained the vote of shareholders, as may
be required by the applicable rules and regulations of the Nasdaq Stock
Market (regardless of whether the Borrower's securities continue to be
traded on the Nasdaq Stock Market), applicable to approve the issuance of
shares of Common Stock in excess of the Issuable Maximum pursuant to the
terms hereof (the "SHAREHOLDER APPROVAL"), then, the Company shall, on such
Date of Exercise or on any Date of Exercise prior to the receipt by the
Company of the Shareholder Approval, shall issue upon exercise hereof a
number of shares of Common Stock equal to the Issuable Maximum and, with
respect to the remainder of this Warrant for which an exercise would result
in an issuance of shares of Common Stock in excess of the Issuable Maximum,
the Company must seek Shareholder Approval in accordance with subsection
(iii) below. The Company and the Holder understand and agree that shares of
Common Stock issued to and then held by the Holder as a result of exercises
of this Warrant shall not be entitled to cast votes on any resolution to
obtain Shareholder Approval pursuant hereto.

                                     11


                  (iii) Shareholder Approval.
                        --------------------

                        (1) The Company shall use its best efforts to obtain
as soon as possible but in no event later than 90 days following the date of
the Loan Agreement or 120 days in the event the proxy materials shall be
reviewed by the Commission, shareholder approval of the issuance of the
Underlying Shares (the "SHAREHOLDER PROPOSAL"), which approval shall meet
the requirements of Nasdaq's Rule 4350(i) of Nasdaq set forth in the NASD
Manual (the "SHAREHOLDER APPROVAL DATE").

                        (2) As soon as practicable following the date of the
Loan Agreement, but in no event more than 30 days following the date of the
Loan Agreement, the Company shall prepare and file with the Commission proxy
materials calling a special meeting (the "SPECIAL MEETING") of its
shareholders seeking approval of the Shareholder Proposal. The Company shall
use its reasonable best efforts to cause such proxy materials to reach the
"no further comment" stage as soon as possible (the "CLEARANCE DATE") and to
hold the Special Meeting as soon as possible following the Clearance Date,
but in no event later than 45 days following the Clearance Date.

                        (3) The Board of Directors shall recommend approval
thereof by the Company's shareholders. The Company shall mail and distribute
its proxy materials for the Special Meeting to its shareholders at least 30
days prior to the date of the Special Meeting and shall actively solicit
proxies to vote for the Shareholder Proposal. The Company shall provide the
Holders an opportunity to review and comment on such proxy materials by
providing (which may be by e-mail) copies of such proxy materials and any
revised preliminary proxy materials to the Holders at least three (3) days
prior to their filing with the Commission. The Company shall provide the
Holders (which may be by e-mail) copies of all correspondence from or to the
Commission or its staff concerning the proxy materials for the Special
Meeting promptly after the same is sent or received by the Company and
summaries of any comments of the Commission's staff which the Company
receives orally promptly after receiving such oral comments. The Company
shall (i) furnish to the Holders and their counsel (which may be by e-mail)
a copy of its definitive proxy materials for the Special Meeting and any
amendments or supplements thereto promptly after the same are first used,
mailed to shareholders or filed with the Commission, (ii) inform the Holders
of the progress of solicitation of proxies for such meeting and (iii) inform
the Holders of any adjournment of the Special Meeting and shall report the
result of the vote of shareholders on the Shareholder Proposal at the
conclusion of the Special Meeting.

                        (4) If for any reason the Shareholder Proposal is not
approved at the Special Meeting, the Company will take such additional acts
or actions as are necessary to hold an additional Special Meeting to
consider the Shareholder Proposal and in conjunction therewith shall hire a
nationally recognized proxy solicitation firm, selected by the Holders which
is reasonably satisfactory to the Company, to assist it in obtaining the
necessary shareholder votes to approve the Shareholder Proposal. The Company
shall bear all costs and expenses of the preparation and filing of any and
all proxy materials and Special Meetings, including but not limited to the
costs and expenses of the proxy solicitation firm if needed.

                                     12


         12. No Fractional Shares. No fractional shares of Warrant Shares will
             --------------------
be issued in connection with any exercise of this Warrant. In lieu of any
fractional shares which would, otherwise be issuable, the Company shall pay
cash equal to the product of such fraction multiplied by the closing price
of one Warrant Share as reported by the applicable Trading Market on the
date of exercise.

         13. Notices. Any and all notices or other communications or deliveries
             -------
hereunder (including, without limitation, any Exercise Notice) shall be in
writing and shall be deemed given and effective on the earliest of (i) the
date of transmission, if such notice or communication is delivered via
facsimile at the facsimile number specified in this Section prior to 6:30
p.m. (New York City time) on a Trading Day, (ii) the next Trading Day after
the date of transmission, if such notice or communication is delivered via
facsimile at the facsimile number specified in this Section on a day that is
not a Trading Day or later than 6:30 p.m. (New York City time) on any
Trading Day, (iii) the Trading Day following the date of mailing, if sent by
nationally recognized overnight courier service, or (iv) upon actual receipt
by the party to whom such notice is required to be given. The addresses for
such communications shall be: (i) if to the Company, to Zoltek Companies,
Inc., 3101 McKelvey Road, St. Louis, Missouri 63044, Attn: Chief Financial
Officer, Facsimile No.: (314) 291-9082, or (ii) if to the Holder, to the
address or facsimile number appearing on the Warrant Register or such other
address or facsimile number as the Holder may provide to the Company in
accordance with this Section.

         14. Warrant Agent. The Company shall serve as warrant agent under this
             -------------
Warrant. Upon 30 days' notice to the Holder, the Company may appoint a new
warrant agent. Any corporation into which the Company or any new warrant
agent may be merged or any corporation resulting from any consolidation to
which the Company or any new warrant agent shall be a party or any
corporation to which the Company or any new warrant agent transfers
substantially all of its corporate trust or shareholders services business
shall be a successor warrant agent under this Warrant without any further
act. Any such successor warrant agent shall promptly cause notice of its
succession as warrant agent to be mailed (by first class mail, postage
prepaid) to the Holder at the Holder's last address as shown on the Warrant
Register.

         15. Miscellaneous.
             -------------

             (a)  This Warrant shall be binding on and inure to the benefit
of the parties hereto and their respective successors and assigns. Subject
to the preceding sentence, nothing in this Warrant shall be construed to
give to any Person other than the Company and the Holder any legal or
equitable right, remedy or cause of action under this Warrant. This Warrant
may be amended only in writing signed by the Company and the Holder and
their successors and assigns.

             (b)  All questions concerning the construction, validity,
enforcement and interpretation of this Warrant shall be governed by and
construed and enforced in accordance with the internal laws of the State of
New York, without regard to the principles of conflicts of law thereof. Each
party agrees that all legal proceedings concerning the interpretations,
enforcement and defense of this Warrant and the transactions herein
contemplated ("PROCEEDINGS") (whether brought against a party hereto or its
respective Affiliates, employees or agents) shall be commenced exclusively
in the state and federal courts sitting in the City of

                                     13


New York, Borough of Manhattan (the "NEW YORK COURTS"). Each party hereto
hereby irrevocably submits to the exclusive jurisdiction of the New York
Courts for the adjudication of any dispute hereunder or in connection
herewith or with any transaction contemplated hereby or discussed herein,
and hereby irrevocably waives, and agrees not to assert in any Proceeding,
any claim that it is not personally subject to the jurisdiction of any New
York Court, or that such Proceeding has been commenced in an improper or
inconvenient forum. Each party hereto hereby irrevocably waives personal
service of process and consents to process being served in any such
Proceeding by mailing a copy thereof via registered or certified mail or
overnight delivery (with evidence of delivery) to such party at the address
in effect for notices to it under this Warrant and agrees that such service
shall constitute good and sufficient service of process and notice thereof.
Nothing contained herein shall be deemed to limit in any way any right to
serve process in any manner permitted by law. Each party hereto hereby
irrevocably waives, to the fullest extent permitted by applicable law, any
and all right to trial by jury in any legal proceeding arising out of or
relating to this Warrant or the transactions contemplated hereby. If either
party shall commence a Proceeding to enforce any provisions of this Warrant,
then the prevailing party in such Proceeding shall be reimbursed by the
other party for its attorney's fees and other costs and expenses incurred
with the investigation, preparation and prosecution of such Proceeding.

             (c)  The headings herein are for convenience only, do not
constitute a part of this Warrant and shall not be deemed to limit or affect
any of the provisions hereof.

             (d)  In case any one or more of the provisions of this Warrant
shall be invalid or unenforceable in any respect, the validity and
enforceability of the remaining terms and provisions of this Warrant shall
not in any way be affected or impaired thereby and the parties will attempt
in good faith to agree upon a valid and enforceable provision which shall be
a commercially reasonable substitute therefor, and upon so agreeing, shall
incorporate such substitute provision in this Warrant.

                [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK,
                           SIGNATURE PAGE FOLLOWS]

                                     14



         IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed by its authorized officer as of the date first indicated above.

                                        ZOLTEK COMPANIES, INC.

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

                                     15



                               EXERCISE NOTICE

To ZOLTEK COMPANIES, INC.:
         The undersigned hereby irrevocably elects to purchase _____________
shares of common stock, par value $0.01 per share, of ZOLTEK COMPANIES, INC.
("COMMON STOCK"), pursuant to Warrant No. [ ], originally issued February
[ ], 2005 (the "WARRANT"), and, if such Holder is not utilizing the cashless
exercise provisions set forth in the Warrant, encloses herewith $________ in
cash, certified or official bank check or checks or other immediately
available funds, which sum represents the aggregate Exercise Price (as
defined in the Warrant) for the number of shares of Common Stock to which
this Exercise Notice relates, together with any applicable taxes payable by
the undersigned pursuant to the Warrant.

         By its delivery of this Exercise Notice, the undersigned represents
and warrants to the Company that in giving effect to the exercise evidenced
hereby the Holder will not beneficially own in excess of the number of
shares of Common Stock (determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934) permitted to be owned under Section 11 of
this Warrant to which this notice relates.

         The undersigned requests that certificates for the shares of Common
Stock issuable upon this exercise be issued in the name of

                                        PLEASE INSERT SOCIAL SECURITY OR
                                        TAX IDENTIFICATION NUMBER


                       (Please print name and address)


                                     16


<TABLE>
                                             Warrant Shares Exercise Log
                                             ---------------------------

<CAPTION>
--------------------------------------------------------------------------------------------------------
Date                     Number of Warrant Shares      Number of Warrant Shares    Number of Warrant
                         Available to be Exercised     Exercised                   Shares Remaining to
                                                                                   be Exercised
--------------------------------------------------------------------------------------------------------
<S>                      <C>                           <C>                         <C>











--------------------------------------------------------------------------------------------------------
</TABLE>

                                     17


                             FORM OF ASSIGNMENT

         [To be completed and signed only upon transfer of Warrant]

         FOR VALUE RECEIVED, the undersigned hereby sells, assigns and
transfers unto ________________________________ the right represented by the
within Warrant to purchase ____________ shares of Common Stock of ZOLTEK
COMPANIES, INC. to which the within Warrant relates and appoints
________________ attorney to transfer said right on the books of the Company
with full power of substitution in the premises.

Dated:   _______________, ____

                                  ---------------------------------------
                                  (Signature must conform in all respects
                                  to name of holder as specified on the
                                  face of the Warrant)



                                  ---------------------------------------
                                  Address of Transferee


                                  ---------------------------------------

                                  ---------------------------------------


In the presence of:

--------------------------


                                     18