<PAGE>



                           LYONDELL CHEMICAL COMPANY
                         Notice of Guaranteed Delivery
                         for Tender of All Outstanding
        9 1/2% Senior Secured Notes due 2008 in exchange for registered
                      9 1/2% Senior Secured Notes due 2008

   This form, or one substantially equivalent hereto, must be used by a holder
to accept the Exchange Offer of Lyondell Chemical Company (the "Issuer"), and
to tender outstanding unregistered 9 1/2% Senior Secured Notes due 2008 (the
"Outstanding Notes") to The Bank of New York, as exchange agent (the "Exchange
Agent") pursuant to the guaranteed delivery procedures described in "The
Exchange Offer--Guaranteed Delivery Procedures" of the Issuer's prospectus
dated      , 2002 (the "Prospectus") and in Instruction 2 to the related Letter
of Transmittal. Any holder who wishes to tender Outstanding Notes pursuant to
such guaranteed delivery procedures must ensure that the Exchange Agent
receives this Notice of Guaranteed Delivery, properly completed and duly
executed, prior to the Expiration Date (as defined below) of the Exchange
Offer. Capitalized terms used but not defined herein have the meanings ascribed
to them in the Prospectus or the Letter of Transmittal.

 The Exchange Offer will expire at 5:00 p.m., New York City time, on      ,
 2002 (the "Expiration Date"), unless sooner terminated or extended.
 Outstanding Notes tendered in the Exchange Offer may be withdrawn at any
 time prior to 5:00 p.m., New York City time, on the Expiration Date for the
 Exchange Offer.


                 The Exchange Agent for the Exchange Offer is:

                              The Bank of New York

        For Delivery By Mail (registered or certified mail recommended),
                         Overnight Delivery or by Hand:

                              The Bank of New York
                                15 Broad Street
                                   16th Floor
                               New York, NY 10005

                              Attn.: Kin Lau

                              Reorganization Unit

            By Facsimile Transmission (eligible institutions only):

                                 (212) 235-2261

                              Attn.: Kin Lau


                             Confirm by telephone:

                              (212) 235-2358


   Delivery of this instrument to an address other than as set forth above, or
transmission via facsimile to a number other than as set forth above, will not
constitute a valid delivery. The instructions accompanying this Notice of
Guaranteed Delivery should be read carefully before the Notice of Guaranteed
Delivery is completed.

   This Notice of Guaranteed Delivery is not to be used to guarantee
signatures. If a signature on a Letter of Transmittal is required to be
guaranteed by an "Eligible Institution" under the instructions thereto, such
signature guarantee must appear in the applicable space in the box provided on
the Letter of Transmittal for guarantee of signatures.
<PAGE>

Ladies and Gentlemen:

   The undersigned hereby tenders to the Issuer, upon the terms and subject to
the conditions set forth in the Prospectus and the related Letter of
Transmittal, receipt of which is hereby acknowledged, the principal amount of
Outstanding Notes set forth below pursuant to the guaranteed delivery
procedures set forth in the Prospectus under the caption "The Exchange Offer--
Guaranteed Delivery Procedures" and in Instruction 2 of the Letter of
Transmittal.

   The undersigned hereby tenders the Outstanding Notes listed below:


<TABLE>
<CAPTION>
                                        Certificate
                                        Numbers(s)
                                       (if known) of
                                     Outstanding Notes   Aggregate  Aggregate
                                     or Account Number   Principal  Principal
                                          at the          Amount     Amount
           Title of Series          Book-entry Facility Represented Tendered
           ---------------          ------------------- ----------- ---------
  <S>                               <C>                 <C>         <C>
  Lyondell Chemical Company 9 1/2%
   Senior Secured Notes due 2008...
</TABLE>

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                            PLEASE SIGN AND COMPLETE
                                          ------------------------------------


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

                                           Signatures of Registered Holder(s)
 -------------------------------------          or Authorized Signatory
  Name(s) of Registered Holders(s)

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

 -------------------------------------
               Address

 -------------------------------------    Dated ________________________, 2002
  Area Code and Telephone Number(s)


   This Notice of Guaranteed Delivery must be signed by the registered
holder(s) of Outstanding Notes exactly as the name(s) of such person(s)
appear(s) on certificates for Outstanding Notes or on a security position
listing as the owner of Outstanding Notes, or by person(s) authorized to become
holder(s) by endorsements and documents transmitted with this Notice of
Guaranteed Delivery. If signature is by a trustee, executor, administrator,
guardian, attorney-in-fact, officer or other person acting in a fiduciary or
representative capacity, such person must provide the following information:

                      Please print name(s) and address(es)

Name(s):

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Capacity:

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Address(es):

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                                       2
<PAGE>

                                   GUARANTEE

                    (Not to be used for signature guarantee)

   The undersigned, a firm which is a member firm of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
or is a commercial bank or trust company having an office or correspondent in
the United States, or is otherwise an "eligible guarantor institution" within
the meaning of Rule 17Ad-15 under the Securities Exchange Act of 1934, hereby
guarantees deposit with the Exchange Agent of the Letter of Transmittal (or
facsimile thereof or agent's message in lieu thereof), together with the
Outstanding Notes tendered hereby in proper form for transfer (or confirmation
of the book-entry transfer of such Outstanding Notes into the Exchange Agent's
account at the DTC described in the Prospectus under the caption "The Exchange
Offers--Book-Entry Transfer" and in the Letter of Transmittal) and any other
required documents, all by 5:00 p.m., New York City time, within five New York
Stock Exchange trading days following the Expiration Date.

Name of Firm:________________________

                                          -------------------------------------
                                                 (Authorized Signature)

Address:_____________________________
                                          Name:________________________________

-------------------------------------
         (Include Zip Code)

                                          Title:_______________________________
                                                 (Please Type or Print)

Area Code and Telephone Number:

-------------------------------------     Date: _________________________, 2002

   Do not send Outstanding Notes with this form. Actual surrender of
Outstanding Notes must be made pursuant to, and be accompanied by, a properly
completed and duly executed Letter of Transmittal and any other required
documents.

                                       3
<PAGE>

                 INSTRUCTIONS FOR NOTICE OF GUARANTEED DELIVERY

   1. Delivery of this Notice of Guaranteed Delivery. A properly completed and
duly executed copy of this Notice of Guaranteed Delivery (or facsimile hereof
or an agent's message and Notice of Guaranteed Delivery in lieu hereof) and any
other documents required by this Notice of Guaranteed Delivery with respect to
the Outstanding Notes must be received by the Exchange Agent at its address set
forth herein prior to the Expiration Date of the Exchange Offer. The method of
delivery of this Notice of Guaranteed Delivery and any other required documents
to the Exchange Agent is at the election and sole risk of the holder, and the
delivery will be deemed made only when actually received by the Exchange Agent.
If delivery is by mail, registered mail with return receipt requested, properly
insured, is recommended. As an alternative to delivery by mail, holders may
wish to consider using an overnight or hand delivery service. In all cases,
sufficient time should be allowed to ensure timely delivery. For a description
of the guaranteed delivery procedures, see Instruction 2 of the Letter of
Transmittal.

   2. Signatures on this Notice of Guaranteed Delivery. If this Notice of
Guaranteed Delivery (or facsimile hereof) is signed by the registered holder(s)
of the Outstanding Notes referred to herein, the signature(s) must correspond
exactly with the name(s) written on the face of the Outstanding Notes without
alteration, enlargement or any change whatsoever. If this Notice of Guaranteed
Delivery (or facsimile hereof) is signed by a participant of the DTC whose name
appears on a security position listing as the owner of the Outstanding Notes,
the signature must correspond with the name shown on the security position
listing as the owner of the Outstanding Notes.

   If this Notice of Guaranteed Delivery (or facsimile hereof) is signed by a
person other than the registered holder(s) of any Outstanding Notes listed or a
participant of the DTC, this Notice of Guaranteed Delivery must be accompanied
by appropriate bond powers, signed as the name(s) of the registered holder(s)
appear(s) on the Outstanding Notes or signed as the name(s) of the participant
shown on the DTC's security position listing.

   If this Notice of Guaranteed Delivery (or facsimile hereof) is signed by a
trustee, executor, administrator, guardian, attorney-in-fact, officer of a
corporation, or other person acting in a fiduciary or representative capacity,
such person should so indicate when signing and submit with the Letter of
Transmittal evidence satisfactory to the Exchange Agent of such person's
authority to so act.

   3. Requests for Assistance or Additional Copies. Questions and requests for
assistance and requests for additional copies of the Prospectus and this Notice
of Guaranteed Delivery may be directed to the Exchange Agent at the address set
forth on the cover page hereof. Holders may also contact their broker, dealer,
commercial bank, trust company or other nominee for assistance concerning the
Exchange Offer.

                                       4