<PAGE>

                                                                 Exhibit 4.5

                                                                   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: October 14, 2004

         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 ____________ 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 $13.00 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 October 14, 2010 (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 October 14, 2004 to which the Company and the original Holder are parties
(the "PURCHASE AGREEMENT").

         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 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.

                                     2

            (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.

         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

                                     3

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 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

                                     4

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 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

                                     5

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.(1)
                -----------------------

                (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, at the option of the Holder for such exercises as it
shall indicate, 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

<FN>
--------
(1) This provision will not be in the Warrants issued to directors or
    officers of the Company.

                                     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 made
pursuant to this subsection 9(d) (including without limitation upon the
redemption or

                                     7

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

                                     8

                (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 Notes or on the 2003
Debentures or 2004 Debentures, 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 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.

                                     9

         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 the
Holder upon any exercise of this Warrant (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
the Holder's for purposes of Section 13(d) of the Exchange Act, does not
exceed 9.999% of the total number of issued and outstanding shares of Common
Stock (including for such purpose the shares of Common Stock issuable upon
such exercise). 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. This provision shall not restrict the
number of shares of Common Stock which a Holder may receive or beneficially
own in order to determine the amount of securities or other consideration
that such Holder may receive in the event of a Fundamental Transaction
involving the Company as contemplated in Section 9 of this Warrant. This
restriction may not be waived.

                 (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

                                     10

exercises of this Warrant at a conversion 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 3,289,196, less such number of
shares of Common Stock as have been issued at a price below the Threshold
Price (1) upon exercise of this Warrant and warrants issued under the 2003
Securities Purchase Agreement and the 2004 Securities Purchase Agreement,
(2) upon conversion of the 2003 Debentures and the 2004 Debentures, and (3)
upon conversion of Notes, or in payment of interests 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 under the Purchase Agreement 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 (or any successor entity or any other Eligible Market on which
the Company's securities then trade), 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 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
as soon as possible, but in any event not later than the 90th day following
such Date of Exercise or the date of such request. 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.

         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

                                     11

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 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

                                     12

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]


                                     13


         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:


                                     14


                               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. 1, originally issued October 14,
2004 (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)

                                     15


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

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












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

                                     16



                             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:


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



                                     17