Document:

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                                                                  EXECUTION COPY

                          REGISTRATION RIGHTS AGREEMENT

         THIS REGISTRATION RIGHTS AGREEMENT ("Agreement"), is made and
entered into as of the 18th day of March, 2000, by and among RENTECH, INC., a
Colorado corporation (the "Company"), and FOREST OIL CORPORATION and ANSCHUTZ
INVESTMENT COMPANY (each of whom is individually referred to as a "Purchaser"
and all of whom collectively are referred to as the "Purchasers").
Capitalized terms used in this Agreement and not otherwise defined herein
shall have the meanings ascribed to them in the Purchase Agreements (as
defined below).

                                   BACKGROUND

         In connection with the consummation of the transactions contemplated
by those certain Stock Purchase Agreements (the "Purchase Agreements") of
even date herewith by and between the Company and each of the Purchasers
respectively in connection with a private placement by the Company pursuant
to Rule 506 under Regulation D of the Securities Act of 1933, as amended, and
the rules and regulations thereunder, or any similar successor statute (the
"1933 Act"), the Company has agreed, upon the terms and subject to the
conditions of the Purchase Agreements, to issue and sell to each of the
Purchasers 1,000,000 shares of Common Stock (the "Purchased Common Shares")
and to issue stock options (the "Options") to each of the Purchasers for the
purchase by each Purchaser of an aggregate of 3,000,000 shares of Common
Stock (as the same may be adjusted in accordance with the agreements
governing such options, the "Option Shares"). Collectively, the Purchased
Common Shares and the Option Shares are hereinafter collectively referred to
as the "Purchased Securities". To induce Purchasers to execute and deliver
their respective Purchase Agreements, the Company has agreed to file a
Registration Statement covering the Purchased Common Shares and the Option
Shares under the 1933 Act and applicable state securities laws.

         For and in consideration of the background circumstances and the
mutual covenants contained herein and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the Company and
the Purchasers hereby agree as follows:

         SECTION 1.    DEFINITIONS.

         As used in this Agreement, the following capitalized terms are used
with the meanings there after ascribed.

                  (a) "Investor" means any Purchaser and any permitted
         transferee or assignee thereof to whom any Purchaser assigns its rights
         under this Agreement and who agrees to become bound by the provisions
         of this Agreement in accordance with Section 9.

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                  (b) "Person" means a corporation, a limited liability company,
         an association, a partnership, an organization, a business, an
         individual, a governmental or political subdivision thereof, or a
         governmental agency.

                  (c) "Register," "Registered," and "Registration" refer to a
         registration effected by preparing and filing one or more Registration
         Statements in compliance with the 1933 Act and pursuant to Rule 415
         under the 1933 Act or any successor rule providing for offering
         securities on a continuous basis ("Rule 415"), and the declaration or
         ordering of effectiveness of such Registration Statement(s) by the
         United States Securities and Exchange Commission (the "SEC").

                  (d) "Registrable Securities" means the Purchased Common
         Shares, and the Option Shares and any shares of capital stock issued or
         issuable with respect to the Purchased Securities or the Option Shares
         as a result of any sale or issuance of Common Stock by the Company for
         less than its then prevailing fair market value, any stock split, stock
         dividend, recapitalization, exchange, or similar event.

                  (e) "Registration Statement" means a registration statement of
         the Company filed under the 1933 Act. Capitalized terms used herein and
         not otherwise defined herein shall have the respective meanings set
         forth in the Purchase Agreement.

         SECTION 2.    REGISTRATION.

                  (a) MANDATORY REGISTRATION. (i) The Company shall use its best
         efforts to prepare, and, on or before the date that is thirty (30) days
         after the date hereof, file with the SEC a Registration Statement or
         Registration Statements (as necessary) on Form S-3 (or, if such form is
         unavailable for such a registration, on such other form as is available
         for such a registration of all of the Registrable Securities) (any of
         which may contain a combined prospectus with other registrations by the
         Company), covering the resale of all of the Registrable Securities,
         which Registration Statement(s), to the extent allowable under the 1933
         Act and the rules promulgated thereunder (including without limitation
         Rule 416), shall state that such Registration Statement(s) also covers
         such indeterminate number of additional shares (the "Indeterminate
         Shares") of Common Stock as may become issuable upon the adjustment of
         the Options as the result of any sale or issuance of Common Stock by
         the Company for less than its then prevailing fair market value or any
         stock splits, stock dividends or similar transactions requiring
         adjustment of the number of Option Shares issuable upon the exercise or
         conversion of the Options in accordance with the Option Agreements.

                           (ii) To the extent the Indeterminate Shares for any
         reason cannot be registered under the Registration Statement(s)
         required under Section 2(a)(i) above, then with respect to such
         Indeterminate Shares, the Company shall use its best efforts to

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         prepare, and, on or before the date that is thirty (30) days after the
         Indeterminate Shares become issuable, file with the SEC a Registration
         Statement or Registration Statements (as necessary) on Form S-3 (or, if
         such form is unavailable for such a registration, on such other form as
         is available for such a registration of all of the Indeterminate
         Shares) (any of which may contain a combined prospectus with other
         registrations by the Company), covering the resale of all of the
         Indeterminate Shares.

                           (iii) A copy of the Registration Statement(s) (and
         each amendment or supplement thereto, and each request for acceleration
         of effectiveness thereof) shall be provided to (and subject to the
         approval of the Investors, which approval shall not be unreasonably
         withheld or denied) the Investors and their counsel prior to its filing
         or other submission.

                           (iv) The Company shall use its best efforts to obtain
         effectiveness of the Registration Statement(s) as soon as practicable.

                  (b) MAINTENANCE OF EFFECTIVENESS; REGISTRATION PERIOD. The
         Company shall use its best efforts to cause the Registration
         Statement(s) relating to the Registrable Securities filed in accordance
         with Section 2(a) to become effective as soon as possible after such
         filing, but in no event later than the Registration Deadline (as
         defined below), and to keep the Registration Statement(s) effective
         pursuant to Rule 415 at all times until the earlier of (i) the date on
         which all of the Registrable Securities have been sold (and no further
         Registrable Securities may be issued in the future) or (ii) the date as
         of which the Investors may immediately sell all of the Registrable
         Securities without restriction pursuant to Rule 144 promulgated under
         the 1933 Act (or successor thereto) or otherwise, not to exceed seven
         (7) years from the effective date(s) of the Registration Statement(s)
         (the "Registration Period").

                  (c) PIGGY-BACK REGISTRATIONS. If at any time prior to the
         expiration of the Registration Period the Company proposes to file with
         the SEC a Registration Statement relating to an offering for its own
         account or the account of others under the 1933 Act of any of its
         securities (other than on Form S-4 or Form S-8 or their then
         equivalents relating to securities to be issued solely in connection
         with any acquisition of any entity or business or equity securities
         issuable in connection with stock option or other employee benefit
         plans) the Company shall promptly send to each Investor who holds
         Registrable Securities written notice of the Company's intention to
         file a Registration Statement and of such Investor's rights under this
         Section 2(c) and, if within twenty (20) days after receipt of such
         notice, such Investor shall so request in writing, the Company shall
         include in such Registration Statement all or any part of the
         Registrable Securities that such Investor requests to be registered,
         subject to the priorities set forth in Section 2(d) below. No right to
         registration of Registrable Securities under this Section

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         2(c) shall be construed to limit any registration required under
         Section 2(a) hereof. The obligations of the Company under this Section
         2(c) may be waived by each individual Investor holding Registrable
         Securities, in its sole discretion, without effect to any other
         Investor. If an offering in connection with which an Investor
         is entitled to registration under this Section 2(c) is an
         underwritten offering, then each Investor whose Registrable
         Securities are included in such Registration Statement
         shall, unless otherwise agreed by the Company, offer and sell such
         Registrable Securities in an underwritten offering using the same
         underwriter or underwriters and, subject to the provisions of this
         Agreement, on the same terms and conditions as other shares of Common
         Stock included in such underwritten offering.

                  (d) PRIORITY IN PIGGY-BACK REGISTRATION RIGHTS. If the
         registration referred to in Section 2(c) is to be an underwritten
         public offering for the account of the Company and the managing
         underwriter(s) advise the Company in writing that, in their reasonable
         good faith opinion, marketing or other factors dictate that a
         limitation on the number of shares of Common Stock which may be
         included in the Registration Statement is necessary to facilitate and
         not adversely affect the proposed offering, then the Company shall
         include in such registration: (i) first, all securities the Company
         proposes to sell for its own account, (ii) second, up to the full
         number of securities proposed to be registered for the account of the
         holders of securities entitled to inclusion of their securities in the
         Registration Statement by reason of demand registration rights, (iii)
         third, the securities requested to be registered by the Investors, pro
         rata based on the number of Registrable Shares each has requested to be
         included in such registration, and (iv) fourth, the other holders of
         securities entitled to participate in the registration, drawn from them
         pro rata based on the number each has requested to be included in such
         registration.

                  (e) ELIGIBILITY FOR FORM S-3. The Company represents, warrants
         and covenants that it has filed and shall file all reports required to
         be filed by the Company with the SEC in a timely manner so as to obtain
         and maintain such eligibility for the use of Form S-3. In the event
         that Form S-3 is not available for sale by the Investors of the
         Registrable Securities, then (i) the Company, with the consent of each
         Investor pursuant to Section 2(a), shall register the sale of the
         Registrable Securities on another appropriate form, such as Form SB-2,
         and (ii) the Company shall undertake to register the Registrable
         Securities on Form S-3 as soon as such form is available.

                  (f) LOCK-UP PERIOD. Each Purchaser agrees (y) not to offer,
         sell, contract to sell or otherwise dispose of any of its Purchased
         Common Shares during the 90-day period beginning on the date of the
         closing of its respective Purchase Agreement, and (z) upon the
         expiration of the aforesaid 90-day period, not to offer, sell, contract
         to sell or otherwise dispose of more than 50% of its Purchased Common
         Shares for an additional 90-day period beginning on the day following
         the expiration of the aforesaid 90-day period.

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         SECTION 3.    RELATED OBLIGATIONS.

         Whenever an Investor has requested that any Registrable Securities
be registered pursuant to Section 2(c) hereof, or at such time as the Company
is obligated to file a Registration Statement with the SEC pursuant to
Section 2(a) hereof, the Company will use its best efforts to effect the
registration of the Registrable Securities in accordance with the respective
method of disposition thereof as required by such provisions and, pursuant
thereto, and the Company shall have the following obligations:

                  (a) The Company shall promptly prepare and file with the SEC a
         Registration Statement with respect to the Registrable Securities
         within the time provided in Section 2(a) for the registration of
         Registrable Securities pursuant to Section 2(a) or Section 2(c), if
         applicable, and use its best efforts to cause such Registration
         Statement(s) relating to Registrable Securities to become effective as
         soon as possible after such filing and in any event within sixty (60)
         days after filing with the SEC (the "Registration Deadline") and
         PROVIDED FURTHER that the Registration Deadline shall not exceed ninety
         (90) days from the date hereof, and keep the Registration Statement(s)
         effective pursuant to Rule 415 at all times until the completion of the
         Registration Period. The Registration Statement(s) (including any
         amendments or supplements thereto and prospectuses contained therein)
         shall not contain any untrue statement of a material fact or omit to
         state a material fact required to be stated therein, or necessary to
         make the statements therein, in light of the circumstances in which
         they were made, not misleading.

                  (b) The Company shall prepare and file with the SEC such
         amendments (including post-effective amendments) and supplements to the
         Registration Statement(s) and the prospectus(es) used in connection
         with the Registration Statement(s), which prospectus(es) are to be
         filed pursuant to Rule 424 promulgated under the 1933 Act, as may be
         necessary to keep the Registration Statement(s) effective at all times
         during the Registration Period, and, during such period, comply with
         the provisions of the 1933 Act with respect to the disposition of all
         Registrable Securities of the Company covered by the Registration
         Statement(s) until such time as all of such Registrable Securities
         shall have been disposed of in accordance with the intended methods of
         disposition by the seller or sellers thereof as set forth in the
         Registration Statement(s). In the event the number of shares available
         under a Registration Statement filed pursuant to this Agreement is
         insufficient to cover all of the Registrable Securities, the Company
         shall amend the Registration Statement, or file a new Registration
         Statement (on the short form available therefor, if applicable), or
         both, so as to cover all of the Registrable Securities, in each case,
         as soon as practicable, but in any event within fifteen (15) days after
         the necessity therefor arises (based on the market price of the Common
         Stock and other relevant factors on which the Company reasonably elects
         to rely) or upon reasonable request therefor by any Investor. The
         Company shall use its best efforts to cause such

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         amendment and/or new Registration Statement to become effective as soon
         as practicable following the filing thereof. For purposes of the
         foregoing provision, the number of shares available under a
         Registration Statement shall be deemed "insufficient to cover all of
         the Registrable Securities" if at any time the number of
         Registrable Securities issued or issuable is in excess of the
         number of shares of Common Stock eligible for resale under the then
         effective Registration Statement(s) filed to cover the Registrable
         Securities in accordance with this Agreement.

                  (c) The Company shall furnish to each Investor whose
         Registrable Securities are included in the Registration Statement(s)
         and its legal counsel, without charge, (i) promptly after the same is
         prepared and filed with the SEC, at least one copy of the Registration
         Statement and any amendment thereto, including financial statements and
         schedules, all documents incorporated therein by reference, and all
         exhibits, the prospectus(es) included in such Registration Statement(s)
         (including each preliminary prospectus) and all correspondence by or on
         behalf of the Company to the SEC or the staff of the SEC and all
         correspondence from the SEC or the staff of the SEC to the Company or
         its representatives, related to such Registration Statement(s), (ii)
         upon the effectiveness of any Registration Statement, such number of
         copies of the prospectus included in such Registration Statement and
         all amendments and supplements thereto as such Investor may reasonably
         request, and (iii) such other documents, including any preliminary
         prospectus, as such Investor may reasonably request in order to
         facilitate the disposition of the Registrable Securities owned by such
         Investor.

                  (d) The Company shall (i) register and qualify the Registrable
         Securities covered by the Registration Statement(s) under such other
         securities or "blue sky" laws of such jurisdictions in the United
         States as any Investor reasonably requests, (ii) prepare and file in
         those jurisdictions, such amendments (including post-effective
         amendments) and supplements to such registrations and qualifications as
         may be necessary to maintain the effectiveness thereof during the
         Registration Period, (iii) take such other actions as may be necessary
         to maintain such registrations and qualifications in effect at all
         times during the Registration Period, and (iv) take all other actions
         reasonably necessary or advisable to qualify the Registrable Securities
         for sale in such jurisdictions, Provided that the Company shall not be
         required in connection therewith or as a condition thereto to qualify
         to do business or to file a general consent to service of process in
         any such states or jurisdictions, and further provided that (anything
         in this Section to the contrary notwithstanding with respect to the
         bearing of expenses) if any jurisdiction in which the securities shall
         be qualified shall require that expenses incurred in connection with
         the qualification of the securities in that jurisdiction be borne by
         selling shareholders pro rata, to the extent required by such
         jurisdiction. The Company shall promptly notify each Investor who holds
         Registrable Securities of the receipt by the Company of any
         notification with respect to the suspension of the registration or
         qualification of any of the Registrable Securities for sale under the
         securities or "blue sky" laws of any jurisdiction

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         in the United States or its receipt of actual notice of the initiation
         or threatening of any proceeding for such purpose.

                  (e) In the event Investors who hold a majority of the
         Registrable Securities being offered in the offering select
         underwriters for the offering, the Company shall enter into and perform
         its obligations under an underwriting agreement, in usual and customary
         form, including, without limitation, customary indemnification and
         contribution obligations, with the underwriters of such offering.

                  (f) As promptly as practicable after becoming aware of such
         event, the Company shall notify each Investor in writing of the
         happening of any event, of which the Company has knowledge, as a result
         of which, the prospectus included in a Registration Statement, as then
         in effect, includes an untrue statement of a material fact or omission
         to state a material fact required to be stated therein or necessary to
         make the statements therein, in light of the circumstances under which
         they were made, not misleading, and promptly prepare a supplement or
         amendment to the Registration Statement to correct such untrue
         statement or omission, and deliver such number of copies of such
         supplement or amendment to each Investor as such Investor may
         reasonably request. The Company shall also promptly notify each
         Investor in writing (i) when a prospectus or any prospectus supplement
         or post-effective amendment has been filed, and when a Registration
         Statement or any post-effective amendment has become effective
         (notification of such effectiveness shall be delivered to each Investor
         by facsimile by the next business day of such effectiveness and by
         overnight mail), (ii) of any request by the SEC for amendments or
         supplements to a Registration Statement or related prospectus or
         related information, and (iii) of the Company's reasonable
         determination that a post-effective amendment to a Registration
         Statement would be appropriate.

                  (g) The Company shall use its best efforts to prevent the
         issuance of any stop order or other suspension of effectiveness of a
         Registration Statement, or the suspension of the qualification of any
         of the Registrable Securities for sale in any jurisdiction and, if such
         an order or suspension is issued, to obtain the withdrawal of such
         order or suspension at the earliest possible moment, and to notify each
         Investor who holds Registrable Securities being sold (and, in the event
         of an underwritten offering, the managing underwriters) of the issuance
         of such order and the resolution thereof, or its receipt of actual
         notice of the initiation, or threatened initiation of any proceeding
         for such purpose.

                  (h) The Company shall permit each Investor a single firm of
         counsel or such other counsel as thereafter designated as selling
         stockholders' counsel by the Investors who hold a majority of the
         Registrable Securities being sold, to review and comment upon the
         Registration Statement(s) and all amendments and supplements thereto at
         least seven (7) days prior to their filing with the SEC, and not file
         any document in a form to

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         which such counsel reasonably objects. The Company shall not submit
         a request for acceleration of the effectiveness of a Registration
         Statement(s) or any amendment or supplement thereto without the prior
         approval of such counsel, which consent shall not be unreasonably
         withheld.

                  (i) At the request of the Investors who hold a majority of the
         Registrable Securities being sold, the Company shall furnish, on the
         date that Registrable Securities are delivered to an underwriter, if
         any, for sale in connection with the Registration Statement (i) if
         required by an underwriter, a letter, dated such date, from the
         Company's independent certified public accountants in form and
         substance as is customarily given by independent certified public
         accountants to underwriters in an underwritten public offering,
         addressed to the underwriters, and (ii) an opinion, dated as of such
         date, of counsel representing the Company for purposes of such
         Registration Statement, in form, scope, and substance as is customarily
         given in an underwritten public offering, addressed to the underwriters
         and the Investors.

                  (j) The Company shall make available for inspection by (i) any
         Investor, (ii) any underwriter participating in any disposition
         pursuant to a Registration Statement, (iii) one firm of attorneys and
         one firm of accountants or other agents retained by each Investor, and
         (iv) one firm of attorneys retained by all such underwriters
         (collectively, the "Inspectors") all pertinent financial and other
         records, and pertinent corporate documents and properties of the
         Company (collectively, the "Records"), as shall be reasonably deemed
         necessary by each Inspector to enable each Inspector to exercise its
         due diligence responsibility, and cause the Company's officers,
         directors, and employees to supply all information which any Inspector
         may reasonably request for purposes of such due diligence; Provided
         However, that each Inspector shall hold in strict confidence and shall
         not make any disclosure (except to an Investor) or use of any Record or
         other information which the Company determines in good faith to be
         confidential, and of which determination the Inspectors are so
         notified, unless (A) the disclosure of such Records is necessary to
         avoid or correct a misstatement or omission in any Registration
         Statement or is otherwise required under the 1933 Act, (B) the release
         of such Records is ordered pursuant to a final, non-appealable subpoena
         or order from a court or government body of competent jurisdiction, or
         (C) the information in such Records has been made generally available
         to the public other than by disclosure in violation of this or any
         other agreement. Each Investor agrees that it shall, upon learning that
         disclosure of such Records is sought in or by a court or governmental
         body of competent jurisdiction or through other means, give prompt
         notice to the Company and allow the Company, at its expense, to
         undertake appropriate action to prevent disclosure of, or to obtain a
         protective order for, the Records deemed confidential.

                  (k) The Company shall hold in confidence and not make any
         disclosure of information concerning an Investor provided to the
         Company unless (i) disclosure of such information is necessary to
         comply with federal or state securities laws, (ii) the disclosure

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         of such information is necessary to avoid or correct a misstatement or
         omission in any Registration Statement, (iii) the release of such
         information is ordered pursuant to a subpoena or other final,
         non-appealable order from a court or governmental body of competent
         jurisdiction, or (iv) such information has been made generally
         available to the public other than by disclosure in violation of this
         or any other agreement. The Company agrees that it shall, upon learning
         that disclosure of such information concerning an Investor is sought in
         or by a court or governmental body of competent jurisdiction or through
         other means, give prompt written notice to such Investor and allow such
         Investor, at the Investor's expense, to undertake appropriate action to
         prevent disclosure of, or to obtain a protective order for, such
         information.

                  (l) The Company shall use its best efforts to secure the
         inclusion for quotation on the Over the Counter Bulletin Board for the
         Registrable Securities, and, to arrange for at least two market makers
         to register with the National Association of Securities Dealers, Inc.
         ("NASD") as such with respect to such Registrable Securities. The
         Company shall pay all fees and expenses in connection with satisfying
         its obligation under this Section 3(l).

                  (m) The Company shall cooperate with the Investors who hold
         Registrable Securities being offered and, to the extent applicable, any
         managing underwriter or underwriters, to facilitate the timely
         preparation and delivery of certificates (not bearing any restrictive
         legend) representing the Registrable Securities to be offered pursuant
         to a Registration Statement and enable such certificates to be in such
         denominations or amounts, as the case may be, as any managing
         underwriter or underwriters or the Investors may reasonably request and
         registered in such names as the managing underwriter or underwriters,
         if any, or the Investors may request. Not later than the date on which
         any Registration Statement registering the resale of Registrable
         Securities is declared effective, the Company shall deliver to its
         transfer agent instructions, accompanied by any reasonably required
         opinion of counsel, that permit sales of unlegended securities in a
         timely fashion that complies with then mandated securities settlement
         procedures for regular way market transactions.

                  (n) The Company shall take all other reasonable actions
         necessary to expedite and facilitate disposition by the Investors of
         Registrable Securities pursuant to a Registration Statement.

                  (o) The Company shall provide a transfer agent and registrar
         of all such Registrable Securities not later than the effective date of
         such Registration Statement.

                  (p) If requested by the managing underwriters or an Investor,
         the Company shall promptly incorporate in a prospectus supplement or
         post-effective amendment such information as the managing underwriters
         and the Investors agree should be included therein relating to the sale
         and distribution of Registrable Securities, including, without

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         limitation, information with respect to the number of Registrable
         Securities being sold to such underwriters, the purchase price being
         paid therefor by such underwriters, and with respect to any other terms
         of the underwritten (or best efforts underwritten) offering of the
         Registrable Securities to be sold in such offering; make all required
         filings of such prospectus supplement or post-effective amendment as
         soon as notified of the matters to be incorporated in such prospectus
         supplement or post-effective amendment; and supplement or make
         amendments to any Registration Statement if requested by a shareholder
         or any underwriter of such Registrable Securities.

                  (q) The Company shall use its best efforts to cause the
         Registrable Securities covered by the applicable Registration Statement
         to be registered with or approved by such other governmental agencies
         or authorities as may be necessary to consummate the disposition of
         such Registrable Securities.

                  (r) The Company shall otherwise use its best efforts to comply
         with all applicable rules and regulations of the SEC in connection with
         any registration hereunder.

         SECTION 4.    OBLIGATIONS OF THE INVESTORS.

                  (a) At least seven (7) days prior to the first anticipated
         filing date of the Registration Statement(s), the Company shall notify
         each Investor in writing of the information the Company requires from
         each such Investor if such Investor elects to have any of such
         Investor's Registrable Securities included in the Registration
         Statement(s). It shall be a condition precedent to the obligations of
         the Company to complete the registration pursuant to this Agreement
         with respect to the Registrable Securities of a particular Investor
         that such Investor shall furnish to the Company such information
         regarding itself, the Registrable Securities held by it, and the
         intended method of disposition of the Registrable Securities held by it
         as shall be reasonably required to effect the registration of such
         Registrable Securities, and shall execute such documents in connection
         with such registration as the Company may reasonably request.

                  (b) Each Investor by such Investor's acceptance of the
         Registrable Securities agrees to cooperate with the Company as
         reasonably requested by the Company in connection with the preparation
         and filing of the Registration Statement(s) hereunder, unless such
         Investor has notified the Company in writing of such Investor's
         election to exclude all of such Investor's Registrable Securities from
         the Registration Statement(s).

                  (c) In the event Investors holding a majority of the
         Registrable Securities being registered determine to engage the
         services of an underwriter, each Investor agrees to enter into and
         perform such Investor's obligations under an underwriting agreement, in
         usual and customary form, including, without limitation, customary
         indemnification and

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         contribution obligations, with the managing underwriter of such
         offering and take such other actions as are reasonably required
         in order to expedite or facilitate the disposition of the Registrable
         Securities, unless such Investor notifies the Company in writing of
         such Investor's election to exclude all of such Investor's Registrable
         Securities from the Registration Statement(s).

                  (d) Each Investor agrees that, upon receipt of any notice from
         the Company of the happening of any event of the kind described in
         Section 3(g) or the first sentence of 3(f), such Investor will
         immediately discontinue disposition of Registrable Securities pursuant
         to the Registration Statement(s) covering such Registrable Securities
         until such Investor's receipt of the copies of the supplemented or
         amended prospectus contemplated by Section 3(g) or the first sentence
         of 3(f) and, if so directed by the Company, such Investor shall deliver
         to the Company (at the expense of the Company) or destroy all copies in
         such Investor's possession, of the prospectus covering such Registrable
         Securities current at the time of receipt of such notice.

                  (e) No Investor may participate in any underwritten
         registration hereunder unless such Investor (i) agrees to sell such
         Investor's Registrable Securities on the basis provided in any
         underwriting arrangements approved by the Investors entitled hereunder
         to approve such arrangements, (ii) completes and executes all
         questionnaires, powers of attorney, indemnities, underwriting
         agreements, and other documents reasonably required under the terms of
         such underwriting arrangements, and (iii) agrees to pay its pro rata
         share of all underwriting discounts and commissions.

         SECTION 5.    EXPENSES OF REGISTRATION.

         All expenses incurred in connection with registrations, filings, or
qualifications pursuant to Sections 2 and 3, including, without limitation,
all registration, listing and qualifications fees, printers and printing
fees, accounting fees, and fees and disbursements of counsel for the Company
and fees and disbursements of one counsel for the Investors, shall be borne
by the Company.

         SECTION 6.    INDEMNIFICATION.

         In the event any Registrable Securities are included in a
Registration Statement under this Agreement:

                  (a) The Company will, and hereby does, indemnify, hold
         harmless, and defend each Investor who holds such Registrable
         Securities, the directors, officers, partners, employees, agents, and
         each Person, if any, who controls any Investor within the meaning of
         the 1933 Act or the Securities Exchange Act of 1934, as amended (the
         "1934 ACT"),

                                       11
<PAGE>

         and any underwriter (as defined in the 1933 Act) for the
         Investors, and the directors and officers of, and each Person, if any,
         who controls, any such underwriter within the meaning of the 1933 Act
         or the 1934 Act (each, an "Indemnified Person"), against any losses,
         claims, damages, liabilities, judgments, fines, penalties, charges,
         costs, attorneys' fees, amounts paid in settlement or expenses, joint
         or several (collectively, "Claims") incurred in investigating,
         preparing, or defending any action, claim, suit, inquiry, proceeding,
         investigation, or appeal taken from the foregoing by or before any
         court or governmental, administrative, or other regulatory agency, body
         or the SEC, whether pending or threatened, whether or not an
         indemnified party is or may be a party thereto ("Indemnified Damages"),
         to which any of them may become subject insofar as such Claims (or
         actions or proceedings, whether commenced or threatened, in respect
         thereof) arise out of or are based upon: (i) any untrue statement or
         alleged untrue statement of a material fact in a Registration Statement
         or any post-effective amendment thereto or in any filing made in
         connection with the qualification of the offering under the securities
         or other "blue sky" laws of any jurisdiction in which Registrable
         Securities are offered ("Blue Sky Filing"), or the omission or alleged
         omission to state a material fact required to be stated therein or
         necessary to make the statements therein, in light of the circumstances
         under which the statements therein were made, not misleading, (ii) any
         untrue statement or alleged untrue statement of a material fact
         contained in any preliminary prospectus if used prior to the effective
         date of such Registration Statement, or contained in the final
         prospectus (as amended or supplemented, if the Company files any
         amendment thereof or supplement thereto with the SEC) or the omission
         or alleged omission to state therein any material fact necessary to
         make the statements made therein, in light of the circumstances under
         which the statements therein were made, not misleading, or, (iii) any
         violation or alleged violation by the Company of the 1933 Act, the 1934
         Act, any other law, including, without limitation, any state securities
         law, or any rule or regulation thereunder relating to the offer or sale
         of the Registrable Securities pursuant to a Registration Statement (the
         matters in the foregoing clauses (i) through (iii) being, collectively,
         "Violations"). Subject to the restrictions set forth in Section 6(d)
         with respect to the number of legal counsel, the Company shall
         reimburse the Investors and each such underwriter or controlling
         person, promptly as such expenses are incurred and are due and payable,
         for reasonable legal fees or other expenses incurred by them in
         connection with investigating or defending any such Claim.

         Notwithstanding anything to the contrary contained herein, the
         indemnification agreement contained in this Section 6(a): (i) shall not
         apply to a Claim arising out of or based upon a Violation which occurs
         in reliance upon and in conformity with information furnished in
         writing to the Company by any Indemnified Person or underwriter for
         such Indemnified Person expressly for use in connection with the
         preparation of the Registration Statement(s) or any such amendment
         thereof or supplement thereto, if such prospectus was timely made
         available by the Company pursuant to Section 3(c); (ii) with respect to
         any preliminary prospectus, shall not inure to the benefit of any such
         person from whom the person asserting any such Claim purchased the
         Registrable Securities that

                                       12
<PAGE>

         are the subject thereof (or to the benefit of any person controlling
         such person) if the untrue statement or mission of material fact
         contained in the preliminary prospectus was corrected in the
         prospectus, as then amended or supplemented, if such prospectus was
         timely made available by the Company pursuant to Section 3(c),
         and the Indemnified Person was promptly advised in writing not to
         use the incorrect prospectus prior to the use giving rise to a
         violation and such Indemnified Person, notwithstanding such advice,
         used the incorrect prospectus; (iii) shall not be available to the
         extent such Claim is based on a failure of the Investor to deliver or
         to cause to be delivered the prospectus made available by the Company;
         and (iv) shall not apply to amounts paid in settlement of any Claim if
         such settlement is effected without the prior written consent of the
         Company, which consent shall not be unreasonably withheld. Such
         indemnity shall remain in full force and effect regardless of any
         investigation made by or on behalf of the Indemnified Person and shall
         survive the transfer of the Registrable Securities by the Investors
         pursuant to Section 9.

                  (b) The Company shall be entitled to receive indemnities from
         underwriters, selling brokers, dealer managers, and similar securities
         industry professionals participating in any distribution, to the same
         extent as provided above, with respect to information such persons so
         furnished in writing expressly for inclusion in the Registration
         Statement(s).

                  (c) Promptly after receipt by an Indemnified Person under this
         Section 6 of notice of the commencement of any action or proceeding
         (including any governmental action or proceeding) involving a Claim,
         such Indemnified Person shall, if a Claim in respect thereof is to be
         made against any indemnifying party under this Section 6, deliver to
         the indemnifying party a written notice of the commencement thereof and
         the indemnifying party shall have the right to participate in, and, to
         the extent the indemnifying party so desires, jointly with any other
         indemnifying party similarly noticed, to assume control of the defense
         thereof with counsel mutually satisfactory to the indemnifying party
         and the Indemnified Person; Provided However, that an Indemnified
         Person shall have the right to retain its own counsel with the fees and
         expenses to be paid by the indemnifying party, if, in the reasonable
         opinion of counsel retained by the indemnifying party, the
         representation by such counsel of the Indemnified Person and the
         indemnifying party would be inappropriate due to actual or potential
         differing interests between such Indemnified Person and any other party
         represented by such counsel in such proceeding. The Company shall pay
         reasonable fees for only one separate legal counsel for the Investors,
         and such legal counsel shall be selected by the Investors holding a
         majority in interest of the Registrable Securities included in the
         Registration Statement to which the Claim relates. The Indemnified
         Person shall cooperate fully with the indemnifying party in connection
         with any negotiation or defense of any such action or claim by the
         indemnifying party and shall furnish to the indemnifying party all
         information reasonably available to the Indemnified Person which
         relates to such action or claim. The indemnifying party shall keep the
         Indemnified Person fully apprised at all

                                       13
<PAGE>

         times as to the status of the defense or any settlement negotiations
         with respect thereto. No indemnifying party shall be liable for any
         settlement of any action, claim or proceeding effected without its
         written consent, Provided However, that the indemnifying party
         shall not unreasonably withhold, delay or condition its consent. No
         indemnifying party shall, without the consent of the Indemnified
         Person, consent to entry of any judgment or enter into any settlement
         or other compromise which does not include as an unconditional term
         thereof the giving by the claimant or plaintiff to such Indemnified
         Person of a release from all liability in respect to such claim or
         litigation. Following indemnification as provided for hereunder,
         the indemnifying party shall be subrogated to all rights of the
         Indemnified Person with respect to all third parties, firms, or
         corporations relating to the matter for which indemnification has been
         made. The failure to deliver written notice to the indemnifying party
         within a reasonable time of the commencement of any such action shall
         not relieve such indemnifying party of any liability to the Indemnified
         Person under this Section 6, except to the extent that the indemnifying
         party is prejudiced in its ability to defend such action.

                  (d) The indemnification required by this Section 6 shall be
         made by periodic payments of the amount thereof during the course of
         the investigation or defense, as and when bills are received or
         Indemnified Damages are incurred.

                  (e) The indemnity agreements contained herein shall be in
         addition to (i) any cause of action or similar right of the Indemnified
         Person against the indemnifying party or others, and (ii) any
         liabilities the indemnifying party may be subject to pursuant to the
         law.

         SECTION 7.    CONTRIBUTION.

         To the extent any indemnification by an indemnifying party is
prohibited or limited by law, the indemnifying party agrees to make the
maximum contribution with respect to any amounts for which it would otherwise
be liable under Section 6 to the fullest extent permitted by law; provided
however, that: (i) no contribution shall be made under circumstances where
the party against whom indemnification is otherwise sought would not have
been liable for indemnification under the fault standards set forth in
Section 6; (ii) no seller of Registrable Securities guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the 1933 Act) shall
be entitled to contribution from any seller of Registrable Securities who was
not guilty of fraudulent misrepresentation, and (iii) contribution by any
seller of Registrable Securities shall be limited in amount to the net amount
of proceeds received by such seller from the sale of such Registrable
Securities.

         SECTION 8.    REPORTS UNDER THE 1934 ACT.

                                       14
<PAGE>

         With a view to making available to the Investors the benefits of
Rule 144 promulgated under the 1933 Act or any other similar rule or
regulation of the SEC that may at any time permit the investors to sell
securities of the Company to the public without registration ("RULE 144"),
the Company agrees to:

                  (a) make and keep public information available, as those terms
         are understood and defined in Rule 144;

                  (b) file with the SEC in a timely manner all reports and other
         documents required of the Company under the 1933 Act and the 1934 Act
         so long as the Company remains subject to such requirements and the
         filing of such reports and other documents is required for the
         applicable provisions of Rule 144; and

                  (c) furnish to each Investor so long as such Investor owns
         Registrable Securities, promptly upon request, (i) a written statement
         by the Company that it has complied with the reporting requirements of
         Rule 144, the 1933 Act, and the 1934 Act, (ii) a copy of the most
         recent annual or quarterly report of the Company and such other reports
         and documents so filed by the Company, and (iii) such other information
         as may be reasonably requested to permit the investors to sell such
         securities pursuant to Rule 144 without registration.

         SECTION 9.    ASSIGNMENT OF REGISTRATION RIGHTS.

         The rights to have the Company register Registrable Securities
pursuant to this Agreement shall be automatically assignable by the Investors
to any permitted transferee of all or any portion of Registrable Securities
according to the provisions of the Purchase Agreements and the Stock Option
Agreements if: (i) the Investor agrees in writing with the transferee or
assignee to assign such rights, and a copy of such agreement is furnished to
the Company within a reasonable time after such assignment; (ii) the Company
is, within a reasonable time after such transfer or assignment, furnished
with written notice of (A) the name and address of such transferee or
assignee, and (B) the securities with respect to which such registration
rights are being transferred or assigned; (iii) immediately following such
transfer or assignment the further disposition of such securities by the
transferee or assignee is restricted under the 1933 Act and applicable state
securities laws; (iv) at or before the time the Company receives the written
notice contemplated by clause (ii) of this sentence the transferee or
assignee agrees in writing with the Company to be bound by all of the
provisions contained herein; (v) such transfer shall have been made in
accordance with the applicable requirements of the Purchase Agreements; (vi)
such transferee shall be an "accredited investor" as that term is defined in
Rule 501 of Regulation D promulgated under the 1933 Act; and (vii) in the
event the assignment occurs subsequent to the date of effectiveness of the
Registration Statement(s) required to be filed pursuant to Section

                                       15
<PAGE>

2(a), the transferee agrees to pay all reasonable expenses of amending or
supplementing such Registration Statement(s) to reflect such assignment.

         SECTION 10.   AMENDMENT OF REGISTRATION RIGHTS.

         Provisions of this Agreement may be amended and the observance
thereof may be waived (either generally or in a particular instance and
either retroactively or prospectively), only with the written consent of the
Company and Investors who hold two-thirds of the Registrable Securities. Any
amendment or waiver effected in accordance with this Section 10 shall be
binding upon each Investor and the Company.

         SECTION 11.   MISCELLANEOUS.

                  (a) A person or entity is deemed to be a holder of Registrable
         Securities whenever such person or entity owns of record such
         Registrable Securities. If the Company receives conflicting
         instructions, notices, or elections from two or more persons or
         entities with respect to the same Registrable Securities, the Company
         shall act upon the basis of instructions, notice, or election received
         from the registered owner of such Registrable Securities.

                  (b) Any notices, consents, waivers, or other communications
         required or permitted to be given under the terms of this Agreement
         must be in writing and will be deemed to have been delivered (i) upon
         receipt, when delivered personally; (ii) upon receipt, when sent by
         facsimile, provided a copy is mailed by U.S. certified mail, return
         receipt requested; (iii) three (3) days after being sent by U.S.
         certified mail, return receipt requested, or (iv) one (1) day after
         deposit with a nationally recognized overnight delivery service, in
         each case properly addressed to the party to receive the same. The
         addresses and facsimile numbers for such communications shall be:

             If to the Company:        RENTECH, INC.
                                       1331 17th Street, Suite 720
                                       Denver, CO  80202
                                       Attn: Ronald C. Butz, Vice President
                                       Telephone:  (303) 298-8008
                                       Facsimile:  (303) 298-8010

             with a copy (which shall not constitute notice) to:

                                       Loren L. Mall, Esq.

                                       16
<PAGE>

                                       Brega & Winters, P.C.
                                       1700 Lincoln Street, Suite 2222
                                       Denver, CO  80203
                                       Telephone:  (303) 866-9400
                                       Facsimile:  (303) 861-9109

                           If to a Purchaser, to its address and facsimile
         number on the Schedule of Purchasers, with copies to such Purchaser's
         counsel as set forth on the Schedule of Purchasers. Each party shall
         provide five (5) days prior written notice to the other party of any
         change in address or facsimile number.

                  (c) Failure of any party to exercise any right or remedy under
         this Agreement or otherwise, delay by a party in exercising such right
         or remedy, shall not operate as a waiver thereof.

                  (d) This Agreement shall be governed by and interpreted in
         accordance with the laws of the State of Colorado without regard to the
         principles of conflict of laws. If any provision of this Agreement
         shall be invalid or unenforceable in any jurisdiction, such invalidity
         or unenforceability shall not affect the validity or enforceability of
         the remainder of this Agreement in that jurisdiction or the validity or
         enforceability of any provision of this Agreement in any other
         jurisdiction.

                  (e) This Agreement, the Purchase Agreements and the Option
         Agreements constitute the entire agreement among the parties hereto
         with respect to the subject matter hereof and thereof. There are no
         restrictions, promises, warranties, or undertakings, other than those
         set forth or referred to herein and therein. This Agreement supersedes
         all prior agreements and understandings among the parties hereto with
         respect to the subject matter hereof.

                  (f) Subject to the requirements of Section 9, this Agreement
         shall inure to the benefit and of and be binding upon the permitted
         successors and assigns of each of the parties hereto.

                  (g) The headings in this Agreement are for convenience of
         reference only and shall not limit or otherwise affect the meaning
         hereof.

                  (h) This Agreement may be executed in two or more identical
         counterparts, each of which shall be deemed an original but all of
         which shall constitute one and the same agreement. This Agreement, once
         executed by a party, may be delivered to the other party hereto by
         facsimile transmission of a copy of this Agreement bearing the
         signature of the party so delivering this Agreement.

                                       17
<PAGE>

                  (i) Each party shall do and perform, or cause to be done and
         performed, all such further acts and things, and shall execute and
         deliver all such other agreements, certificates, instruments, and
         documents, as the other party may reasonably request in order to carry
         out the intent and accomplish the purposes of this Agreement and the
         consummation of the transactions contemplated hereby.

                            [Signature Page Follows]

                                       18
<PAGE>

         IN WITNESS WHEREOF, the parties have caused this Registration Rights
Agreement to be duly executed as of day and year first above written.

                                    COMPANY:

                                    RENTECH, INC.

                                    By:/s/ Dennis L. Yakobson
                                       --------------------------------
                                       Dennis L. Yakobson, President

FOREST OIL CORPORATION              ANSCHUTZ INVESTMENT COMPANY

By:/s/ David H. Keyte               By:/s/ Clifford Hickey
   ------------------------------      --------------------------------
       Authorized Agent                    Authorized Agent

Address:_________________________   Address:___________________________

Telephone:_______________________   Telephone:_________________________

Facsimile:_______________________   Facsimile:_________________________<PAGE>

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, FOREST OIL CORPORATION ("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, 2001 (the "Expiration Date"), 2,000,000 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
$1.25 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 $1.25 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 $2,500,000.00.

         (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 (or 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, and if they are unable to do so within such
time period, the Board and/or the Optionee may 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 increase 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.

                                       1
<PAGE>

         2. OPTION PERIOD. This Option may be exercised not later than 5:00
P.M., Denver time, on December 31, 2001. 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. ADJUSTMENTS 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 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 product 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

                                       2
<PAGE>

         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 at 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 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 nonsurviving entity as is attributable to 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.

                                       3
<PAGE>

         (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 insure 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 insure 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 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

                                       4
<PAGE>

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.

                  (ii) "Control Basis" means the valuation of securities by
         determining on an 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.

                  (v) "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).

                  (vi) "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.

                  (vii) "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

                                       5
<PAGE>

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.

         (b) OPTION AGENT. 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 (which consent shall not be unreasonably withheld or delayed)
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.

                                       6
<PAGE>

         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).

                            [SIGNATURE PAGE FOLLOWS]

                                       7
<PAGE>

         IN WITNESS WHEREOF, the Company and the Optionee have caused this
Option to be executed as of March 18, 2000.

OPTIONEE:

FOREST OIL CORPORATION                     RENTECH, INC.

By:/s/ David H. Keyte                      By:/s/ Dennis L. Yakobson
   ----------------------------------         ---------------------------------
     David H. Keyte,                            Dennis L. Yakobson, President
     Executive Vice President

     Forest Oil Corporation
     1600 Broadway, Suite 2200
     Denver, Colorado 80202

<PAGE>

                                  RENTECH, INC.

                    NOTICE OF EXERCISE OF STOCK OPTION ISSUED

To:      Rentech, Inc.
         1331 17th Street, Suite 720
         Denver, CO 80202

         I hereby exercise my Option dated ______________________________ to
purchase ____________________ shares of $.01 par value common stock of the
Company at the option exercise price of $_______________ per share. Enclosed
is a certified or cashier's check in the total amount of $_______________, or
payment in such other form as the Company has specified and agreed to accept,
which is described at the bottom of this notice.

         I represent to you that I am acquiring said shares for investment
purposes and not with a view to any distribution thereof. I understand that
my stock certificate may bear an appropriate legend restricting the transfer
of my shares and that a stop transfer order may be placed with the Company's
transfer agent with respect to such shares.

         I request that my shares be issued in the name of:

_______________________________________________________________________________
                 (Print your name in the form in which you wish
                         to have the shares registered)

_______________________________________________________________________________
                            (Social Security Number)

_______________________________________________________________________________
                               (Street and Number)

_______________________________________________________________________________
(City)                               (State)                          (Zip Code)

                                              Optionee:

Dated: _______________________, 20____.       ________________________________

Signature:                                    By:_____________________________
                                                 Authorized Agent

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