Document:

<PAGE>   1

                                                                     EXHIBIT 4.3

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY NOT BE PLEDGED,
SOLD, OFFERED FOR SALE, TRANSFERRED, OR OTHERWISE DISPOSED OF IN THE ABSENCE OF
REGISTRATION UNDER OR EXEMPTION FROM SUCH ACT AND ALL APPLICABLE STATE
SECURITIES LAWS.

                                  RENTECH, INC.

                    OPTION TO PURCHASE SHARES OF COMMON STOCK

                                       OF

                                  RENTECH, INC.

         FOR VALUE RECEIVED, _________________________ ("Optionee"), is entitled
to purchase, subject to the provisions of this Option, from RENTECH, INC., a
Colorado corporation ("Company"), at any time not later than 5:00 P.M., Denver
time, on December 31, ______ (the "Expiration Date"), ______________ shares of
common stock, having $.01 par value per share, of the Company ("Common Stock")
at an exercise price, subject to adjustment as set forth below, of $______ per
share. The number of shares of Common Stock to be received upon the exercise of
this Option and the price to be paid for a share of Common Stock are subject to
adjustment from time to time as hereinafter set forth.

         1.       Option Price: Fair Market Value.

         (a) The option price is $______ for each share of Common Stock, as the
same may be adjusted from time to time in accordance with Section 4 hereof;
provided, however, that the maximum aggregate option price for all shares of
Common Stock issuable upon the exercise of this Option (or the aggregate of all
Options resulting from the subdivision of this Option) shall not exceed
$_____________.

         (b) For purposes of this Option, but only if and to the extent
applicable, the fair market value of such Common Stock (the "Fair Market Value")
shall be determined as follows: (i) if the Common Stock is listed on a national
securities exchange or admitted to unlisted trading privileges on such exchange,
then the Fair Market Value shall be the last reported sale price of the Common
Stock on the composite tape of such exchange, or, if no such sale is made on any
trading day, the average closing bid and asked prices for such day on the
composite tape of such exchange; or (ii) if the Common Stock is not so listed or
admitted to unlisted trading privileges, the Fair Market Value shall be the
average of the last reported bid and asked prices reported by the National
Association of Securities Dealers Quotation System (of if not quoted on NASDAQ,
by the National Quotation Bureau, Inc. or other reporting medium, including the
Over the Counter Bulletin Board); or (iii) otherwise the Fair Market Value shall
be an amount not less than book value determined in such reasonable manner as
may be prescribed by the Board of Directors of the Company (the "Board"). If an
Optionee disagrees with the Fair Market Value as determined by the Board
pursuant to clause (iii) of the preceding sentence, such Optionee may provide
written notice of such disagreement to the Company that states in reasonable
detail the basis of the disagreement and such Optionee's determination of the
Fair Market Value (a "Dispute Notice"). The Board and the Optionee shall attempt
to resolve the disagreement as to the Fair Market Value within ten days after
the Dispute Notice is given to the Company,

<PAGE>   2

and if they are unable to do so within such time period, the Board and/or the
Optionee my submit the dispute to a "big five" independent accounting firm (that
directly represents neither the Company nor the Optionee and the selection of
which shall be mutually agreed upon) (the "Accountant") in Denver, Colorado. The
determination of the Accountant as to the Fair Market Value shall be conclusive
and binding upon the Optionee and the Company. The Company and the Optionee
shall bear equally the fees and expenses of the Accountant unless the
determination of the Accountant results in a net in crease of the Fair Market
Value of more than five percent over the amount determined by the Board, in
which case the Company shall be solely responsible for the payment of such fees
and expenses.

                  2. Option Period. This Option may be exercised not later than
5:00 P.M., Denver time, on December 31, _____. The Option granted shall be void
if not exercised during the option period.

                  3. Exercise of Option. Unless the Option is terminated as
provided pursuant to this Option, an Optionee may exercise this option for up
to, but not in excess of, the amounts of shares subject to the Option. The
Option may be exercised, in whole or in part, and at any time and from time to
time within its term.

                  (a) Method of Exercise. This Option shall be exercisable by a
written notice delivered to the Company (the "Notice of Exercise") which shall:

                           (i) State the election to exercise the Option, the
number of shares of Common Stock in respect of which it is being exercised
(which must be in multiples of one hundred shares), and the entity in whose name
the stock certificate or certificates for such shares of Common Stock is to be
registered, with that entity's address and taxpayer identification number; and

                           (ii) Be signed by the person or persons entitled to
exercise the Option and, if the Option is being exercised by any entity or
entities other than the Optionee, be accompanied by proof, satisfactory to
counsel for the Company, of the right of such entity or entities to exercise the
Option.

                  (b) Payment of Option Price. Payment of the option price for
any shares of Common Stock with respect to which the Option is being exercised
shall be by wire transfer, cash, certified check or other means acceptable to
the Company, and shall be delivered with the Notice of Exercise. The certificate
or certificates for shares of Common Stock as to which the Option shall be
exercised shall be registered in the name of the entity or entities indicated in
the notice of exercise in accordance with Section 3(a)(i).

                  (c) Restrictions on Exercise. As a condition to exercise of
this Option, the Company may require the person or entity exercising this Option
to make any representation and warranty as may be required by any applicable law
or regulation.

                  4. Adjustment Upon Changes in Capitalization. In order to
prevent dilution of the rights granted under this Option, the option price and
the number of shares purchasable hereunder shall be subject to adjustment from
time to time as follows:

                  (a) Adjustment of Number of Shares of Common Stock Upon
Issuance of Common Stock or Common Stock Equivalents. If and whenever the
Company issues or sells, or in accordance with paragraph (b) is deemed to have
issued or sold, any Common Stock for a consideration per share less than the
Fair Market Value per share at the time of such issue or sale (not including the
issuance of the Permitted Stock (as defined below)) then forthwith upon such
issue or sale, the shares of Common Stock subject to this

<PAGE>   3

Option (the "Subject Shares") will be increased by multiplying such number by a
fraction, (A) the numerator of which is the Fair Market Value per share at the
time of such issue or sale and (B) the denominator of which is the amount
determined by dividing (a) the sum of (1) the produce derived by multiplying the
Fair Market Value per share at the time of such issue or sale times the number
of shares of Common Stock outstanding on a Fully-Diluted Basis immediately prior
to such issue or sale, plus (2) the aggregate consideration, if any, received by
the Company upon such issue or sale, by (b) the number of shares of Common Stock
outstanding on a Fully-Diluted Basis immediately after such issue or sale.

                  (b) Effect on Subject Shares of Certain Events. For purposes
of determining the adjusted Subject Shares under paragraph (a) above, the
following will be applicable:

                           (i) Issuance of Common Stock Equivalents. If the
Company in any manner grants any Common Stock Equivalent (as defined below)
(other than Permitted Stock) and the lowest price per share for which any one
share of Common Stock of the Company is issuable upon the exercise of any such
Common Stock Equivalent is less than the Fair Market Value of the Common Stock
at the time of the granting of such Common Stock Equivalent, then all of such
shares of Common Stock will be deemed to have been issued and sold by the
Company for such price per share (other than pursuant to antidilutive
adjustments to the Options). For purposes of this paragraph, the "lowest price
per share for which any one share is issuable" will be equal to the sum of the
lowest amounts of consideration (if any) received or receivable by the Company
with respect to any one share upon the exercise of the Common Stock Equivalent
(whether by conversion, exchange or otherwise) or other similar indication of
the price per share as of the time of granting (such as the floor value for
stock appreciation rights). No further adjustment of the Subject Shares will be
made upon the actual issue of such shares of Common Stock or upon the exercise
of any right under the Common Stock Equivalents.

                           (ii) Change in Option Price or Conversion Rate. If
the purchase price provided for in any Common Stock Equivalent (other than
Permitted Stock), the additional consideration, if any, payable upon the issue,
conversion or exchange of any Common Stock Equivalent, or the rate at which any
Common Stock Equivalent is convertible into or exchangeable for shares of Common
Stock changes at any time, the Subject Shares in effect at the time of such
change will be readjusted to the Subject Shares which would have been in effect
t such time had such Common Stock Equivalent still outstanding provided for such
changed purchase price, additional consideration or changed conversion rate, as
the case may be, at the time initially granted, issued or sold.

                           (iii) Treatment of Expired and Unexercised Common
Stock Equivalents. Upon the expiration of any Common Stock Equivalent or the
termination of any right to convert or exchange any Common Stock Equivalent
without the exercise of such Common Stock Equivalent, the Subject Shares then in
effect will be adjusted to the Subject Shares which would have been in effect at
the time of such expiration or termination had such Common Stock Equivalent, to
the extent outstanding immediately prior to such expiration or termination,
never been issued.

                           (iv) Calculation of Consideration Received. If any
Common Stock or Common Stock Equivalents (other than Permitted Stock) are issued
or sold or deemed to have been issued or sold for cash, the consideration
received therefor will be deemed to be the net amount received by the Company.
In case any Common Stock or Common Stock Equivalents (other than Permitted
Stock) are issued or sold for a consideration other than cash, the amount of the
consideration other than cash received by the Company will be the fair market
value of such consideration. In case any Common Stock or Common Stock
Equivalents (other than Permitted Stock) are issued to the owners of the
non-surviving entity in connection

<PAGE>   4

with any merger in which the Company is the surviving entity, the amount of
consideration therefor will be deemed to be the fair market value of such
portion of the net assets and business of the non-surviving entity as is
attributable top such Common Stock or Common Stock Equivalents, as the case may
be.

                           (v) Integrated Transactions. In case any Common Stock
Equivalent (other than Permitted Stock) is issued in connection with the issue
or sale of other securities of the Company, together comprising one integrated
transaction in which no specific consideration is allocated to such Common Stock
Equivalent by the parties thereto, the Common Stock Equivalent will be deemed to
have been issued without consideration.

                           (vi) Record Date. If the Company takes a record of
the holders of Common Stock for the purpose of entitling them (A) to receive a
dividend or other distribution payable in Common Stock or Common Stock
Equivalents or (B) to subscribe for or purchase Common Stock or Common Stock
Equivalents, then such record date will be deemed to be the date of the issue or
sale of the 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.

                  (c) Subdivision or Combination of Common Stock. If the Company
at any time subdivides (by any stock split, stock dividend, recapitalization or
otherwise) one or more classes of its outstanding Common Stock into a greater
number of shares of Common Stock, the Subject Shares in effect immediately prior
to such subdivision will be proportionately increased. If the Company at any
time combines (by reverse stock split or otherwise) one or more classes of its
outstanding shares of Common Stock, the Subject Shares in effect immediately
prior to such combination will be proportionately decreased.

                  (d) Reorganization, Reclassification, Consolidation, Merger or
Sale. Any recapitalization, reorganization, reclassification, consolidation,
merger, sale of all or substantially all of the Company's assets to another
person or entity or other transaction which is effected in such a way that
holders of Common Stock are entitled to receive (either directly or upon
subsequent liquidation) stock, securities or assets with respect to or in
exchange for Common Stock is referred to herein as "Organic Change." Prior to
the consummation of any Organic Change, the Company will make appropriate
provision (in form and substance reasonably satisfactory to the Optionees
holding Options representing a majority of the Subject Shares issuable under all
Options then outstanding) to ensure that each of the Optionees will thereafter
have the right to acquire in lieu of the Subject Shares immediately theretofore
acquirable and receivable upon the exercise of such Optionee's Option, such
shares of stock, securities or assets as may be issued or payable with respect
to or in exchange for the Subject Shares immediately theretofore acquirable and
receivable upon exercise of such Optionee's Option had such Organic Change not
taken place. In any such case, the Company will make appropriate provision (in
form and substance satisfactory to the Optionees holding Options representing a
majority of the Subject Shares issuable under all Options then outstanding) with
respect to such Optionees' rights and interests to ensure that the provisions of
this Section 4 will thereafter be applicable to the Options (including, in the
case of any such consolidation, merger or sale in which the successor entity or
purchasing entity is other than the Company, an immediate adjustment of the
option price to the value for the Common Stock reflected by the terms of such
consolidation, merger or sale, and a corresponding immediate adjustment in the
Subject Shares, if the value so reflected is less than the option price in
effect immediately prior to such consolidation, merger or sale). The Company
will not effect any such consolidation, merger or sale, unless prior to the
consummation thereof, the successor entity (if other than the Company) resulting
from consolidation or merger or the corporation purchasing such assets assumes
by written instrument (in form and substance satisfactory to the Optionees), the
obligation to deliver to each

<PAGE>   5

such Optionee such shares of stock, securities or assets as, in accordance with
the foregoing provisions, such Optionee may be entitled to acquire.

                  (e) Notices.

                           (i) Immediately upon any adjustment of the Subject
Shares, the Company will give written notice thereof to the Optionee, setting
forth in reasonable detail and certifying the calculation of such adjustment.

                           (ii) The Company will give written notice to the
Optionee at least twenty (20) days prior to the date on which the Company closes
its books or takes a record (A) with respect to any dividend or distribution
upon the Common Stock, (B) with respect to any pro rata subscription offer to
holders of Common Stock or (C) for determining rights to vote with respect to
any Organic Change, dissolution or liquidation.

                           (iii) The Company will also give written notice to
the Optionees at least twenty (20) days prior to the date on which any Organic
Change, dissolution or liquidation will take place.

                  (f) Liquidating Dividends. If the Company declares or pays a
dividend or makes a distribution upon the Common Stock payable otherwise than in
cash out of earnings or earned surplus (determined in accordance with generally
accepted accounting principles) except for a dividend payable in Common Stock (a
"Liquidating Dividend"), then the Company will pay to each Optionee at the time
of payment thereof the Liquidating Dividend which would have been paid to such
Optionee on the Common Stock had the Options been fully exercised immediately
prior to the date on which a record is taken for such Liquidating Dividend, or,
if no record is taken, the date as of which the record holders of Common Stock
entitled to such dividends are to be determined.

                  (g) Certificate of Adjustment. In each case of an adjustment
or readjustment of the option price for the number of shares of Common Stock or
other securities issuable upon exercise of the Options, if the Option is then
exercisable pursuant to this Section 4, the Company, at its expense, shall
compute such adjustment or readjustment in accordance with the provisions hereof
and prepare a certificate showing such adjustment or readjustment, and shall
mail such certificate, by first class mail, postage prepaid, to each registered
Optionee at the Optionee's address as shown in the Company's books. The
certificate shall set forth such adjustment or readjustment, showing in detail
the facts upon which such adjustment or readjustment is based, including a
statement of (i) the consideration received or deemed to be received by the
Company for any additional shares of Common Stock issued or sold or deemed to
have been issued or sold, (ii) the option price at the time in effect, (iii) the
number of additional shares of Common Stock, and (iv) the type and amount, if
any, of other property which at the time would be received upon exercise of
Options.

                  (h) Certain Definitions. As used in this Section 4, the
following terms shall have the meanings ascribed to them:

                           (i) "Common Stock Equivalent" means any option,
warrant, right or similar security exercisable into, exchangeable for, or
convertible to Common Stock or the economic equivalent value of Common Stock,
other than any Permitted Stock.

<PAGE>   6

                           (ii) "Control Basis" means the valuation of
securities by determining on any aggregate basis the fair market value of all
securities of such type on the basis of the securities being sold in the
aggregate to a third party buyer in an arm's length transaction with conveyance
of control, without discount for minority interests, illiquidity or restrictions
on transfer, and then dividing such amount by the number of all securities of
such type on a Fully-Diluted Basis.

                           (iii) "Fair Market Value" means (a) as to securities
regularly traded in the organized securities markets, the average of the Closing
Price for the security in question for the thirty (30) trading days immediately
preceding the date of determination; and (b) as to all securities not regularly
traded in the securities markets and other property, the fair market value of
such securities, on a Control Basis, or property as of the date of the delivery
of a notice from a Optionee necessitating the determination of fair market value
(unless some other date of valuation is provided herein) as determined in good
faith by the Board (provided that any such determination by the Board shall be
subject to the same rights of dispute and resolution on the part of the Optionee
as set forth in Section 1(b) hereof). Notwithstanding the foregoing, the Fair
Market Value of any shares of Common Stock shall be as determined in accordance
with Section 1(b).

                           (iv) "Fully-Diluted Basis" when used means including
as outstanding all Common Stock and Common Stock Equivalents including, without
limitation, the Common Stock issuable upon exercise of Options.

                           (v) "Permitted Stock" shall include all shares of
Common Stock or Common Stock Equivalents issued or issuable on or prior to the
date of this Option.

         5. Notices. Each notice relating to this Option shall be in writing
and delivered in person or by certified mail to the proper address. Each notice
shall be deemed to have been given on the date it is received. Each notice to
the Company shall be addressed to it at its principal office, attention of the
Secretary. Each Optionee or other person or persons then entitled to exercise
the Option shall be addressed to the Optionee at the Optionee's address set
forth below the Optionee's signature. Anyone to whom a notice may be given under
this Option may designate a new address by notice to that effect.

         6. Benefits of Option. All obligations imposed upon the Company and all
rights granted to the Optionee under this Option shall be binding upon the
Company's successors. All obligations imposed upon the Optionee and all rights
granted to the Company under this Option shall be binding upon the Optionee's
successors or assignees. This Option shall be the sole and exclusive source of
any and all rights which the Optionee, and successors or assignees of Optionee,
may have in respect to any options for purchase of shares of Common Stock
granted hereunder.

         7. Transfer of Option.

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

<PAGE>   7

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

                  (c) Transferability and Non-negotiability of Option. This
Option may not be transferred or assigned, in whole or in part, without
compliance with all applicable federal and state securities laws by the
transferor and the transferee (including the delivery of investment
representation letters and legal opinions reasonably satisfactory to the
Company's outside counsel, if such are requested by the Company) and without the
prior written consent of the Company except that the Optionee may assign its
rights hereunder in whole or in part, to (i) any entity or person that directly,
or indirectly through one or more intermediaries, controls, is controlled by, or
is under common control with Optionee (an "Affiliate") or (ii) any director,
officer, employee, representative or agent of Optionee or any of its Affiliates.
Subject to the provisions of this Option, title to this Option may be
transferred by endorsement and delivery in the same manner as a negotiable
instrument transferable by endorsement and delivery.

                  (d) Exchange of Option Upon a Transfer. On surrender of this
Option for exchange, properly endorsed and subject to the provisions of this
Option with respect to compliance with the Securities Act of 1933, as amended
(the "Act"), and with the limitations on assignments and transfers contained in
this Section 7, the Company at its expense shall issue to or on the order of the
Optionee a new Option or Options of like tenor, in the name of the Optionee or
as the Optionee (on payment by the Optionee of any applicable transfer taxes)
may direct, for the number of shares of Common Stock issuable upon exercise
hereof.

                  (e) Compliance with Securities Laws.

                           (i) The Optionee of this Option, by acceptance
hereof, acknowledges that this Option and the shares of Common Stock to be
issued upon exercise hereof or conversion thereof are being acquired solely for
the Optionee's own account and not as a nominee for any other party, and for
investment, and that the Optionee will not offer, sell or otherwise dispose of
this Option or any shares of Common Stock to be issued upon exercise hereof or
conversion thereof except under circumstances that will not result in a
violation of the Act or any state securities laws. Upon exercise of this Option,
the Optionee shall, if requested by the Company, confirm in writing, in a form
reasonably satisfactory to the Company, that the shares of Common Stock so
purchased are being acquired solely for the Optionee's own account and not as a
nominee for any other party, for investment, and not with a view toward
distribution or resale.

                           (ii) This Option and all shares of Common Stock
issued upon exercise hereof or conversion thereof shall be stamped or imprinted
with a legend in substantially the following form (in addition to any legend
required by state securities laws):

                  THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND
MAY NOT BE PLEDGED, SOLD, OFFERED FOR SALE, TRANSFERRED, OR OTHERWISE DISPOSED
OF IN THE ABSENCE OF REGISTRATION UNDER OR EXEMPTION FROM SUCH ACT AND ALL
APPLICABLE STATE SECURITIES LAWS.

The Company may place an appropriate stop transfer order with the Company's
transfer agent with respect to the shares of Common Stock represented by such
certificates.

<PAGE>   8

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

         9. Amendments.

                  (a) Any term of this Option may be amended only with the
written consent of the Board and the Optionee.

                  (b) No waivers of, or exceptions to, any term, condition or
provision of this Option, in any one or more instances, shall be deemed to be,
or construed as, a further or continuing waiver of any such term, condition or
provision.

         10. Governing Law. This Option shall be governed by and construed in
accordance with the laws of the State of Colorado (without giving effect to the
choice of law principles thereof).

         IN WITNESS WHEREOF, the Company and the Optionee have caused this
Option to be executed as of ____________________.

OPTIONEE:

                                       RENTECH, INC.

By:                                    By:
   ---------------------------------      ---------------------------------
     Authorized Agent                       Dennis L. Yakobson, President<PAGE>   1
                                                                     EXHIBIT 4.4

THE SECURITIES REPRESENTED BY THIS CERTIFICATE AND SHARES ISSUABLE UPON EXERCISE
OF THIS WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1993, AS
AMENDED, AND MAY NOT BE OFFERED FOR SALE, SOLD OR OTHERWISE DISPOSED OF EXCEPT
PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT FILED UNDER THE SECURITIES ACT
OF 1933, AS AMENDED, OR PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER SUCH
ACT. THE HOLDER OF THIS WARRANT AND ANY SHARES ISSUED PURSUANT TO THIS WARRANT
AGREES THAT THE COMPANY MAY REFUSE TO ISSUE SUCH SHARES OR TRANSFER THIS WARRANT
OR SUCH SHARES UNLESS THE COMPANY RECEIVES EVIDENCE SATISFACTORY TO IT AS TO
COMPLIANCE WITH SUCH EXEMPTIONS.

THESE SECURITIES HAVE NOT BEEN REGISTERED WITH THE UNITED STATES SECURITIES AND
EXCHANGE COMMISSION UNDER THE 1933 ACT, AS AMENDED, OR THE SECURITIES COMMISSION
OF ANY STATE UNDER ANY STATE SECURITIES LAW. THEY ARE BEING OFFERED PURSUANT TO
AN EXEMPTION FROM REGISTRATION UNDER REGULATION S ("REGULATION S") PROMULGATED
UNDER THE 1933 ACT. THESE SECURITIES MAY NOT BE OFFERED, SOLD OR OTHERWISE
TRANSFERRED IN THE UNITED STATES OR TO U. S. PERSONS (AS THAT TERM IS DEFINED IN
REGULATION S) UNLESS SUCH SECURITIES ARE REGISTERED UNDER THE 1933 ACT AND
APPLICABLE STATE SECURITIES LAWS, OR SUCH OFFER, SALE OR TRANSFER IS MADE
PURSUANT TO AN EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SAID LAWS.
HEDGING TRANSACTIONS MAY NOT BE CONDUCTED IN THESE SECURITIES UNLESS IN
COMPLIANCE WITH THE 1933 ACT.

VOID AFTER 5:00 P.M., DENVER TIME, ON _______________, ____________, OR IF NOT A
BUSINESS DAY, AS DEFINED HEREIN, AT 5:00 P.M., DENVER TIME, ON THE NEXT BUSINESS
DAY.

                               WARRANT TO PURCHASE
                            ______________ SHARES OF
                                  RENTECH, INC.

         This certifies that, for good and valuable consideration, the
sufficiency of which is hereby acknowledged, ___________________________, whose
address is _______________________________________________, and its registered,
permitted assigns (collectively, the "Warrantholder"), is entitled to purchase
from Rentech, Inc., a corporation incorporated under the laws of the state of
Colorado (the Company), subject to the terms and conditions hereof, at any time
before 5:00 P.M., Denver time, on _______________, _________, (or, if such day
is not a Business Day, at or before 5:00 P.M., Denver time, on the next
following Business Day), ______________ shares of fully paid and nonassessable
Common Stock, par value $.01 per share, at the Exercise Price. The Exercise
Price and the number of shares purchasable hereunder are subject to adjustment
from time to time as provided in Article III hereof. The provisions of this
Warrant are subject in all respects to the provisions of the Securities
Subscription Agreement between the Warrantholder and Rentech, Inc. dated the
same date as this Warrant. The

<PAGE>   2

provisions of the Securities Subscription Agreement are incorporated in this
Warrant and made a part herein.

                                    ARTICLE I

         Section 1.01: Definition of Terms. As used in this Warrant, the
following capitalized terms shall have the following respective meanings:

                  (a) Business Day: A day other than a Saturday, Sunday or other
         day on which banks in the State of Colorado are authorized by law to
         remain closed.

                  (b) Common Stock: Common Shares, $.01 par value, of the
         Company.

                  (c) Common Stock Equivalents: Securities that are convertible
         into or exercisable for shares of Common Stock.

                  (d) Exchange Act: The Securities Exchange Act of 1934, as
         amended.

                  (e) Exercise Price: $___________ per Warrant Share, as such
         price may be adjusted from time to time pursuant to Article III hereof.

                  (f) Expiration Date: 5:00 P.M., Denver time, on ____________,
         ________, or if such day is not a Business Day, the next succeeding day
         which is a Business Day.

                  (g) Holder: A holder of Warrants.

                  (h) NASD: National Association of Securities Dealers, Inc.,
         and NASDAQ: NASD Automated Quotation System.

                  (i) Person: An individual, partnership, joint venture,
         corporation, trust, unincorporated organization or government or any
         department or agency thereof.

                  (j) SEC: The Securities and Exchange Commission or any other
         federal agency at the time administering the Securities Act or the
         Exchange Act.

                  (k) Securities Act: The Securities Act of 1933, as amended.

                  (l) Warrants: This Warrant and all other warrants that may be
         issued in its or their place, originally issued to Azure Energy Fund
         Inc.

                  (m) Warrantholder: The Person to whom this Warrant is
         originally issued, or any successor in interest to whom it has been
         transferred, in whose name this Warrant is registered upon the books to
         be maintained by the Company for that purpose. Any successor in
         interest must meet the qualifications of a subscriber, and adhere to
         the requirements of a

                                      -2-
<PAGE>   3

         subscriber, as set forth in the Securities Subscription Agreement. Only
         such successors in interest shall be deemed "permitted assigns" and
         only such assignments shall be deemed "permitted transfers" for
         purposes of this Warrant.

                  (n) Warrant Shares: Common Stock, Common Stock Equivalents and
         other securities purchased or purchasable upon exercise of the
         Warrants.

                  (o) $ or Dollars: United States dollars.

                                   ARTICLE II

                        DURATION AND EXERCISE OF WARRANT

         Section 2.01: Duration of Warrant. The Warrantholder may exercise this
Warrant at any time and from time to time before 5:00 P.M., Denver time, on the
Expiration Date. If this Warrant is not exercised on or before the Expiration
Date, it shall become void, and all rights hereunder shall thereupon cease.

         Section 2.02: Exercise of Warrant.

                  (a) The Warrantholder may exercise this Warrant, in whole or
         in part, by presentation and surrender of this Warrant to the Company
         at its corporate office at 1331 17th Street, Suite 720, Denver,
         Colorado 80202, or at the office of its stock transfer agent, if any,
         with the Subscription Form annexed hereto duly executed and accompanied
         by payment of the full Exercise Price for each Warrant Share to be
         purchased by means of a cashier's check, wire transfer, or other
         immediately available good funds.

                  (b) Upon receipt of this Warrant with the Subscription Form
         fully executed and accompanied by payment of the aggregate Exercise
         Price for the Warrant Shares for which this Warrant is then being
         exercised, the Company shall cause to be issued certificates for the
         total number of whole shares of Common Stock for which this Warrant is
         being exercised (adjusted to reflect the effect of the anti-dilution
         provisions contained in Article III hereof, if any, and as provided in
         Section 2.04 hereof) in such denominations as are requested for
         delivery to the Warrantholder, and the Company shall thereupon deliver
         such certificates to the Warrantholder. The Warrantholder shall be
         deemed to be the holder of record of the shares of Common Stock
         issuable upon such exercise, notwithstanding that the stock transfer
         books of the Company shall then be closed or that certificates
         representing such shares of Common Stock may not then be actually
         delivered to the Warrantholder. Notwithstanding any other provision of
         this Warrant, if at the time this Warrant is exercised and the Warrant
         Shares issuable upon exercise of this Warrant are not registered, the
         Company may require the Warrantholder to make such representations, may
         place such legends on certificates representing the Warrant Shares, and
         may place such stop transfer instructions and other transfer
         restrictions as may be reasonably required in the opinion of counsel to
         the Company to permit the Warrant Shares to be issued without such
         registration. The restrictive

                                      -3-
<PAGE>   4

         endorsements contained in Exhibit A to the Securities Subscription
         Agreement will be placed on the certificates.

                  (c) In case the Warrantholder shall exercise this Warrant with
         respect to less than all of the Warrant Shares that may be purchased
         under this Warrant, the Company shall execute a new Warrant in the form
         of this Warrant for the balance of such Warrant Shares and deliver such
         new Warrant to the Warrantholder.

                  (d) The Company shall pay any and all stock transfer and
         similar taxes which may be payable in respect of the issue of this
         Warrant or in respect of the issue of any Warrant Shares.

         Section 2.03: Reservation of Shares. The Company hereby agrees that, at
all times following the execution of this Warrant, it will reserve for issuance
and delivery upon exercise of this Warrant such number of shares of Common Stock
or other shares of capital stock of the Company from time to time issuable upon
exercise of this Warrant. All such shares shall be duly authorized, and when
issued upon such exercise, shall be validly issued, fully paid and
non-assessable, free and clear of all liens, security interests, charges and
other encumbrances or restrictions on sale and free and clear of all preemptive
rights.

         Section 2.04: Fractional Shares. The Company shall not be required to
issue any fraction of a share of its capital stock in connection with the
exercise of this Warrant, and in any case where the Warrantholder would, except
for the provisions of this Section 2.04, be entitled under the terms of this
Warrant to receive a fraction of a share upon the exercise of this Warrant, the
Company shall, upon the exercise of this Warrant and receipt of the Exercise
Price, issue the greatest number of whole shares purchasable upon exercise of
this Warrant for which payment in full of the Exercise Price has been received.
The Company shall not be required to make any cash or other adjustment in
respect of such fraction of a share to which the Warrantholder would otherwise
be entitled.

         Section 2.05: Listing. Prior to the issuance of any shares of Common
Stock upon exercise of this Warrant, the Company shall secure the listing of
such shares of Common Stock upon each national securities exchange or automated
quotation systems, if any, upon which shares of Common Stock are then listed
(subject to official notice of issuance upon exercise of this Warrant) and shall
maintain, so long as any other shares of Common Stock shall be so listed, such
listing of all shares of Common Stock from time to time issuable upon the
exercise of this Warrant; and the Company shall so list on each national
securities exchange or automated quotation system, and shall maintain such
listing of, any other shares of capital stock of the Company issuable upon the
exercise of this Warrant if and so long as any shares of the same class shall be
listed on such national securities exchange or automated quotation system.

                                      -4-
<PAGE>   5

                                   ARTICLE III

                      ADJUSTMENT OF SHARES OF COMMON STOCK
                         PURCHASABLE AND EXERCISE PRICE

         The Exercise Price and the number and kind of Warrant Shares shall be
subject to adjustment from time to time upon the happening of certain events as
provided in this Article III.

         Section 3.01: Mechanical Adjustments.

                  (a) If at any time prior to the exercise of this Warrant in
         full, the Company shall (i) declare a dividend or make a distribution
         on the Common Stock payable in shares of its Common Stock; (ii)
         subdivide, reclassify or recapitalize the outstanding Common Stock into
         a greater number of shares of Common Stock; (iii) combine, reclassify
         or recapitalize its outstanding shares of Common Stock into a smaller
         number of shares of Common Stock, or (iv) issue any shares of its
         capital stock by reclassification of its Common Stock (including any
         such reclassification in connection with a consolidation or a merger in
         which the Company is the continuing corporation), the Exercise Price in
         effect at the time of the record date of such dividend, distribution,
         subdivision, combination, reclassification or recapitalization shall be
         adjusted so that the Warrantholder shall be entitled to receive the
         aggregate number and kind of shares which, if this Warrant had been
         exercised in full immediately prior to such event, he would have owned
         upon such exercise and been entitled to receive by virtue of such
         dividend, distribution, subdivision, combination, reclassification or
         recapitalization. Any adjustment required by this paragraph 3.01(a)
         shall be made successively and become effective immediately after the
         record date, in the case of a dividend or distribution, or the
         effective date, in the case of a subdivision, combination,
         reclassification or recapitalization, to allow the purchase of such
         aggregate number and kind of shares.

                  (b) If at any time prior to the exercise of this Warrant in
         full, the Company shall fix a record date for the issuance or making a
         distribution to all holders of the Common Stock (including any such
         distribution to be made in connection with a consolidation or merger in
         which the Company is to be the continuing corporation) of evidences of
         its indebtedness, any other securities of the Company or any cash,
         property or other assets or securities, including without limitation
         shares of a subsidiary's capital stock (excluding a common stock
         dividend, combination, reclassification, recapitalization or issuance
         referred to in Section 3.01(a)), regular cash dividends or cash
         distributions in the ordinary course of business or subscription
         rights, options or warrants for Common Stock or Common Stock
         Equivalents (any such nonexcluded event being herein called a Special
         Dividend), then, except as provided in paragraph 3.01(c), the Exercise
         Price shall be decreased immediately after the record date for such
         Special Dividend to a price determined by multiplying the Exercise
         Price then in effect by a fraction, the numerator of which shall be the
         then current market price of the Common Stock (as defined in Section
         3.01(e)) on such record date less the fair market value (as determined
         by the Company's Board of Directors) of the evidences

                                      -5-
<PAGE>   6

         of indebtedness, securities or property, or other assets issued or
         distributed in such Special Dividend applicable to one share of Common
         Stock or of such subscription rights or warrants applicable to one
         share of Common Stock, and the denominator of which shall be the then
         current market price per share of Common Stock (as so determined). Any
         adjustment required by this paragraph 3.01(b) shall be made
         successively effective on the record date for the Special Dividend and
         in the event that such distribution is not so made, the Exercise Price
         shall again be adjusted to be the Exercise Price that was in effect
         immediately prior to such record date.

                  (c) If at any time prior to the exercise of this Warrant in
         full, the Company shall make a distribution to all holders of the
         Common Stock of stock of a subsidiary or securities convertible into or
         exercisable for such stock, then in lieu of an adjustment in the
         Exercise Price or the number of Warrant Shares purchasable upon the
         exercise of this Warrant, each Warrantholder, upon the exercise hereof
         at any time after such distribution, shall be entitled to receive from
         the Company, such subsidiary or both, as the Company shall determine,
         the stock or other securities to which such Warrantholder would have
         been entitled if such Warrantholder had exercised this Warrant
         immediately prior thereto, all subject to further adjustment as
         provided in this Article III, and the Company shall reserve, for the
         life of the Warrant, such securities of such subsidiary or other
         corporation; provided, however, that no adjustment in respect of
         dividends or interest of such stock or other securities shall be made
         during the term of this Warrant or upon its exercise.

                  (d) Whenever the Exercise Price payable upon exercise of each
         Warrant is adjusted pursuant to one or more of paragraphs (a), (b) and
         (c) of this Section 3.01, the number of Warrant Shares issuable upon
         payment of the Warrant Price shall simultaneously be adjusted by
         multiplying the number of Warrant Shares issuable upon exercise of each
         Warrant immediately prior to such adjustment by the Exercise Price in
         effect immediately prior to such adjustment and dividing the product so
         obtained by the Exercise Price, as adjusted.

                  (e) For the purpose of any computation under this Section
         3.01, the current market price per share of Common Stock at any date
         shall be deemed to be the average of the daily closing prices for 20
         consecutive trading days commencing 30 trading days before such date.
         The closing price for each day shall be the last sale price regular way
         or, in case no such reported sales take place on such day, the average
         of the last reported bid and asked prices regular way, in either case
         on the principal national securities exchange on which the Common Stock
         is admitted to trading or listed, or if not listed or admitted to
         trading on such exchange, the representative closing bid price as
         reported by NASDAQ, or other similar organization if NASDAQ is no
         longer reporting such information, or if not so available, the fair
         market price as determined in good faith by the Board of Directors of
         the Company.

                  (f) No adjustment in the Exercise Price shall be required
         unless such adjustment would require an increase or decrease of at
         least ten cents ($.10) in such price; provided, however, that any
         adjustments which by reason of this paragraph (f) are not required to
         be

                                      -6-
<PAGE>   7

         made shall be carried forward and taken into account in any subsequent
         adjustment. All calculations under this Section 3.01 shall be made to
         the nearest cent or to the nearest one-hundredth of a share, as the
         case may be. Notwithstanding anything in this Section 3.01 to the
         contrary, the Exercise Price shall not be reduced to less than the then
         existing par value, if any, of the Common Stock as a result of any
         adjustment made hereunder.

                  (g) In the event that at any time, as a result of any
         adjustment made pursuant to Section 3.01(a), the Warrantholder
         thereafter shall become entitled to receive any shares of the Company
         other than Common Stock, thereafter the number of such other shares so
         receivable upon exercise of any Warrant shall be subject to adjustment
         from time to time in a manner and on terms as nearly equivalent as
         practicable to the provisions with respect to the Common Stock
         contained in Section 3.01(a).

                  (h) In the case of an issue of additional Common Stock or
         Common Stock Equivalents for cash, the consideration received by the
         Company therefor, without deducting therefrom any discount or
         commission or other expenses paid by the Company for any underwriting
         of, or otherwise in connection with, the issuance thereof, shall be
         deemed to be the amount received by the Company therefor. To the extent
         that such issuance shall be for a consideration other than cash, then,
         except as herein otherwise expressly provided, the amounts of such
         consideration shall be deemed to be the fair value of such
         consideration at the time of such issuance as reasonably determined in
         good faith by the Board of Directors of the Company. The term issue
         shall include the sale or other disposition of shares held by or on
         account of the Company or in the treasury of the Company, but until so
         sold or otherwise disposed of such shares shall not be deemed
         outstanding.

         Section 3.02: Notices of Adjustment. Whenever the number of Warrant
Shares or the Exercise Price is adjusted as herein provided, the Company shall
prepare and deliver forthwith to the Warrantholder a certificate signed by its
President, and by any Vice President, Treasurer or Secretary, setting forth the
adjusted number of shares purchasable upon the exercise of this Warrant and the
Exercise Price of such shares after such adjustment, setting forth a brief
statement of the facts requiring such adjustment and setting forth the
computation by which adjustment was made. The certificate of any independent
firm of public accountants of recognized standing selected by the Board of
Directors of the Company shall be conclusive evidence of the arithmetic
correctness of any computation made under this Section 3.

         Section 3.03: No Adjustment for Dividends. Except as provided in
Section 3.01 of this Agreement, no adjustment in respect of any cash dividends
shall be made during the term of this Warrant or upon the exercise of this
Warrant.

         Section 3.04: Preservation of Purchase Rights in Certain Transactions.
In case of any consolidation or merger of the Company with or into another
Person (other than a merger with a subsidiary in which the Company is the
continuing corporation and that does not result in any reclassification, capital
reorganization or other change of outstanding shares of Common Stock) or in case
of any sale, lease, transfer or conveyance to another corporation of the
property and assets

                                      -7-
<PAGE>   8

of the Company as an entirety or substantially as an entirety, the Company
shall, as a condition to such transaction cause such successor or purchasing
corporation, as the case may be, to execute with the Warrantholder an agreement
granting the Warrantholder the right thereafter, upon payment of the Exercise
Price in effect immediately prior to such transaction, to receive upon exercise
of this Warrant the kind and amount of shares and other securities and property
which he would have owned or have been entitled to receive as a result of such
transaction had this Warrant been exercised immediately prior to such action.
Such agreement shall provide for adjustments in respect of such shares of stock
and other securities and property, which shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Article III and shall
provide that such rights may be exercised at any time prior to the Expiration
Date. In the event that in connection with any such transaction, additional
shares of Common Stock shall be issued in exchange, conversion, substitution or
payment, in whole or in part, for, or of, a security of the Company other than
Common Stock, any such issue shall be treated as an issue of Common Stock
covered by the provisions of Article III. The provisions of this Section 3.04
shall similarly apply to successive reclassifications, capital reorganizations,
consolidations, mergers, sales or conveyance.

         Section 3.05: Form of Warrant After Adjustments. The form of this
Warrant need not be changed because of any adjustments in the Exercise Price or
the number or kind of the Warrant Shares, and Warrants theretofore or thereafter
issued may continue to express the same price and number and kind of shares as
are stated in the Warrant, as initially issued.

         Section 3.06: Treatment of Warrantholder. Prior to due presentment for
registration of transfer of this Warrant, the Company may deem and treat the
Warrantholder as the absolute owner of this Warrant (notwithstanding any
notation of ownership or other writing hereon) for all purposes and shall not be
affected by any notice to the contrary.

                                   ARTICLE IV

                          OTHER PROVISIONS RELATING TO
                             RIGHTS OF WARRANTHOLDER

         Section 4.01: No Rights as Shareholders: Notice to Warrantholders.
Nothing contained in this Warrant shall be construed as conferring upon the
Warrantholder or his or its transferees the right to vote or to receive
dividends or to consent or to receive notice as a shareholder in respect of any
meeting of shareholders for the election of directors of the Company or of any
other matter, or any rights whatsoever as shareholders of the Company. The
Company shall give notice to the Warrantholder by registered mail if at any time
prior to the expiration or exercise in full of the Warrants, any of the
following events shall occur:

                  (a) the Company shall authorize the payment of any dividend to
         all holders of Common Stock;

                  (b) the Company shall authorize the issuance to all holders of
         Common Stock of any additional shares of Common Stock or Common Stock
         Equivalents or of rights, options

                                      -8-
<PAGE>   9

         or warrants to subscribe for or purchase Common Stock or Common Stock
         Equivalents or of any other subscription rights, options or warrant;

                  (c) a dissolution, liquidation or winding up of the Company;
         or

                  (d) a capital reorganization or reclassification of the Common
         Stock (other than a subdivision or combination of the outstanding
         Common Stock) or any consolidation or merger of the Company with or
         into another corporation (other than a consolidation or merger in which
         the Company is the continuing corporation and that does not result in
         any reclassification or change of Common Stock outstanding) or in the
         case of any sale or conveyance to another corporation of the property
         of the Company as an entirety or substantially as an entirety.

Such giving of notice shall be completed at least 15 Business Days prior to the
date fixed as a record date or effective date or the date of closing of the
Company's stock transfer books for the determination of the shareholders
entitled to such dividend, distribution, or subscription rights, or for the
determination of the shareholders entitled to vote on such proposed merger,
consolidation, sale, conveyance, dissolution, liquidation or winding up. Such
notice shall specify such record date or the date of closing the stock transfer
books, as the case may be. Failure to provide such notice shall not affect the
validity of any action taken in connection with such dividend, distribution or
subscription rights, or proposed merger, consolidation, sale, conveyance,
dissolution, liquidation or winding up.

         Section 4.02: Lost, Stolen, Mutilated or Destroyed Warrants. If this
Warrant is lost, stolen, mutilated or destroyed, the Company may, upon receipt
by the Company of evidence of ownership reasonably satisfactory to it and on
such terms as to indemnity or otherwise as it may in its discretion impose
(which shall, in the case of a mutilated Warrant, include the surrender
thereof), issue a new Warrant of like denomination and tenor as, and in
substitution for, this Warrant.

         Section 4.03: Split-Up, Combination, Exchange and Transfer of Warrants.
This Warrant may be split up, combined or exchanged for another Warrant or
Warrants containing the same terms to purchase a like aggregate number of
Warrant Shares. If the Warrantholder desires to split up, combine or exchange
this Warrant, he or it shall make such request in writing delivered to the
Company and shall surrender to the Company this Warrant and any other Warrants
to be so split-up, combined or exchanged. Upon any such surrender for a
split-up, combination or exchange, the Company shall execute and deliver to the
person entitled thereto a Warrant or Warrants, as the case may be, as so
requested. The Company shall not be required to effect any split-up, combination
or exchange which will result in the issuance of a Warrant entitling the
Warrantholder to purchase upon exercise a fraction of a share of Common Stock or
a fractional Warrant.

         Section 4.04: Registration Rights. The Warrant Shares, once issued, are
subject to the rights and benefits of the Registration Rights Agreement
pertaining to the Warrant Shares, between the Company and Warrantholder;
provided, however, that notwithstanding anything in such Registration Rights
Agreement to the contrary, the Company hereby consents to the transfer of the
registration

                                      -9-
<PAGE>   10

rights contained therein with respect to the Warrant Shares to the extent that
transfers of the Warrant and the Warrant Shares are permitted hereunder.

         Section 4.05: Redemption. This Warrant may be redeemed by the Company
at any time after sixty (60) days from the date of its original issuance and
prior to the Expiration Date upon at least thirty (30) days' written notice (the
"Notice of Redemption") to the holder of this Warrant for $.05 per Warrant Share
if the closing high bid quotation of the Company's common stock exceeds one
hundred fifty percent (150%) of the Exercise Price for a period of twenty (20)
consecutive trading days immediately preceding the mailing by the Company of the
Notice of Redemption. The Company agrees not to give a Notice of Redemption
unless the shares of common stock underlying the Warrant are included in a
registration statement filed with the Securities and Exchange Commission that is
then effective. The Notice of Redemption shall be sent to the last known address
of the Holder of this Warrant as maintained on the books and records of the
Company. The redemption date shall be fixed in the Notice of Redemption and
shall be not earlier than thirty (30) days after the date of mailing of the
Notice of Redemption. Upon receipt of a Notice of Redemption, the Holder of this
Warrant may exercise this Warrant to the extent of the number of Warrant Shares
called for redemption until the last business day prior to the redemption date.
A "business day" shall mean any day other than Saturday, Sunday or other day on
which banks are required or authorized to be closed in the City of Denver or the
State of Colorado. If on the redemption date the Company shall have paid the
redemption price or shall have reserved and set apart an amount sufficient to
pay the redemption price, then this Warrant shall expire to the extent of the
number of Warrant Shares called for redemption pursuant to the Notice of
Redemption. Warrants called for redemption in whole or in part shall be tendered
to the Company on or before the redemption date. The redemption price shall be
paid to the Warrantholder within three (3) business days after the redemption
date, and shall be delivered by check sent to the last known address of the
warrant holder maintained on the books and records of the Company.

                                    ARTICLE V

                                  OTHER MATTERS

         Section 5.01: Amendments and Waivers. The provisions of this Warrant,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waiver or consents to departures from the provisions hereof
may not be given unless the Company has obtained the written consent of Holders
of at least a majority of the outstanding Warrants. Holders shall be bound by
any consent authorized by this section whether or not certificates representing
such Warrants have been marked to indicate such consent.

         Section 5.02: Governing Law. This Warrant shall be governed by and
construed in accordance with the laws of the state of Colorado.

         Section 5.03: Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstances, is
held invalid, illegal or unenforceable, the

                                      -10-
<PAGE>   11

validity, legality and enforceability of any such provisions in every other
respect and of the remaining provisions contained herein shall not be affected
or impaired thereby.

         Section 5.04: Computations of Consent. Whenever the consent or approval
of Holders of a specified percentage of Warrants is required hereunder, Warrants
held by the Company or its affiliates (other than the Warrantholder or
subsequent Holders if they are deemed to be such affiliates solely by reason of
their holdings of such Warrants) shall not be counted in determining whether
such consent or approval was given by the Holders of such required percentage.

         Section 5.05: Notice. Any notices or certificates by the Company to the
Holder and by the Holder to the Company shall be deemed delivered if in writing
and delivered in person or by registered mail (return receipt requested) to the
Holder at the following address:

                           --------------------------
                           --------------------------
                           --------------------------
                           Attn:
                                ---------------------

or, if the Holder has designated by notice in writing to the Company any other
address, to such other address. If notice is to the Company, such notice is to
be addressed to Rentech, Inc. at:

                           1331 17th Street, Suite 720
                           Denver, CO 80202
                           Attention:  Chief Operating Officer

         The Company may change its address by written notice to the Holder and
the Holder may change its address by written notice to the Company.

         Section 5.06: Investment Representation of the Holder. By accepting
delivery of this Warrant, the Holder represents to the Company that it has
acquired this Warrant solely for its own account for investment and not with a
view to distribution or sale in violation of the Securities Act, but subject,
nevertheless, to any requirement of law that the disposition of the Holder's
property be at all times within its control. The Holder represents that it
understands that this Warrant has been issued in a transaction that is exempt
from the registration requirements of the Securities Act and that this Warrant
must be held by the Holder and may not be resold unless subsequently registered
under the Securities Act or an exemption from such registration is available,
and if so resold, may only be resold and assigned with the shares of Common
Stock of the Company acquired by the Warrantholder concurrently with this
Warrant and only in accordance with the provisions of the Securities
Subscription Agreement. The Holder also represents that it understands and
acknowledges that this Warrant may only be exercised by the Warrantholder or a
permitted assignee.

                                      -11-
<PAGE>   12

         IN WITNESS WHEREOF, this Warrant has been duly executed by the Company
as of the ______ day of _______________, ___________.

WARRANTHOLDER:                          RENTECH, INC.

By:                                     By:
   ------------------------------          -------------------------------------
Name:                                   Name:  James P. Samuels
Title:                                  Title: Vice President--Finance

                                      -12-

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00019-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00019-of-00352.parquet"}]]