<PAGE>

                                                                  Exhibit 24.2.1

                        LYONDELL CHEMICAL NEDERLAND, LTD.

                                POWER OF ATTORNEY

     WHEREAS, LYONDELL CHEMICAL NEDERLAND, LTD., a Delaware corporation (the
"Company"), a wholly owned subsidiary of Lyondell Chemical Company ("Lyondell"),
intends to file with the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), a Registration
Statement on Form S-3, including one or more prospectuses, with such amendment
or amendments thereto, whether pre-effective or post-effective, in each case as
may be necessary or appropriate, together with any and all exhibits and other
documents having relation to said Registration Statement (collectively, the
"Registration Statement"), in connection with potential future issuances of
securities registered thereby by Lyondell, the Company or their affiliate
co-registrants.

     NOW, THEREFORE, the undersigned, in his or her capacity as a director or
officer, or both, as the case may be, of the Company, does hereby appoint Kerry
A. Galvin and T. Kevin DeNicola and each of them severally, his or her true and
lawful attorneys or attorney with power to act with or without the others and
with full power of substitution and resubstitution, to execute in his or her
name, place and stead, in his or her capacity as a director or officer or both,
as the case may be, of the Company, the Registration Statement and all
instruments necessary or incidental in connection therewith, with such amendment
or amendments thereto in each case as may be necessary or appropriate, together
with any and all exhibits and other documents relating thereto as said attorneys
or any of them shall deem necessary or incidental in connection therewith, and
to file the same or cause the same to be filed with the Commission. Each of said
attorneys shall have full power and authority to do and perform in the name and
on behalf of the undersigned, in any and all capacities, every act whatsoever
necessary or desirable to be done to the premises, as fully and to all intents
and purposes as the undersigned might or could do in person, the undersigned
hereby ratifying and approving the acts of said attorneys and each of them.

     IN WITNESS WHEREOF, the undersigned has executed this instrument on this
7th day of May, 2002.

                                  /s/ Morris Gelb
                                  --------------------------------------------
                                  MORRIS GELB
<PAGE>

                        LYONDELL CHEMICAL NEDERLAND, LTD.

                                POWER OF ATTORNEY

     WHEREAS, LYONDELL CHEMICAL NEDERLAND, LTD., a Delaware corporation (the
"Company"), a wholly owned subsidiary of Lyondell Chemical Company ("Lyondell"),
intends to file with the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), a Registration
Statement on Form S-3, including one or more prospectuses, with such amendment
or amendments thereto, whether pre-effective or post-effective, in each case as
may be necessary or appropriate, together with any and all exhibits and other
documents having relation to said Registration Statement (collectively, the
"Registration Statement"), in connection with potential future issuances of
securities registered thereby by Lyondell, the Company or their affiliate
co-registrants.

     NOW, THEREFORE, the undersigned, in his or her capacity as a director or
officer, or both, as the case may be, of the Company, does hereby appoint Kerry
A. Galvin and T. Kevin DeNicola and each of them severally, his or her true and
lawful attorneys or attorney with power to act with or without the others and
with full power of substitution and resubstitution, to execute in his or her
name, place and stead, in his or her capacity as a director or officer or both,
as the case may be, of the Company, the Registration Statement and all
instruments necessary or incidental in connection therewith, with such amendment
or amendments thereto in each case as may be necessary or appropriate, together
with any and all exhibits and other documents relating thereto as said attorneys
or any of them shall deem necessary or incidental in connection therewith, and
to file the same or cause the same to be filed with the Commission. Each of said
attorneys shall have full power and authority to do and perform in the name and
on behalf of the undersigned, in any and all capacities, every act whatsoever
necessary or desirable to be done to the premises, as fully and to all intents
and purposes as the undersigned might or could do in person, the undersigned
hereby ratifying and approving the acts of said attorneys and each of them.

     IN WITNESS WHEREOF, the undersigned has executed this instrument on this
7th day of May, 2002.




                             /s/ Robert T. Blakely
                             --------------------------------------------------
                             ROBERT T. BLAKELY
<PAGE>

                        LYONDELL CHEMICAL NEDERLAND, LTD.

                                POWER OF ATTORNEY

     WHEREAS, LYONDELL CHEMICAL NEDERLAND, LTD., a Delaware corporation (the
"Company"), a wholly owned subsidiary of Lyondell Chemical Company ("Lyondell"),
intends to file with the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), a Registration
Statement on Form S-3, including one or more prospectuses, with such amendment
or amendments thereto, whether pre-effective or post-effective, in each case as
may be necessary or appropriate, together with any and all exhibits and other
documents having relation to said Registration Statement (collectively, the
"Registration Statement"), in connection with potential future issuances of
securities registered thereby by Lyondell, the Company or their affiliate
co-registrants.

     NOW, THEREFORE, the undersigned, in his capacity as a director or officer,
or both, as the case may be, of the Company, does hereby appoint Kerry A.
Galvin, as his true and lawful attorney with power to act with or without the
others and with full power of substitution and resubstitution, to execute in his
name, place and stead, in his capacity as a director or officer or both, as the
case may be, of the Company, the Registration Statement and all instruments
necessary or incidental in connection therewith, with such amendment or
amendments thereto in each case as may be necessary or appropriate, together
with any and all exhibits and other documents relating thereto as said attorney
shall deem necessary or incidental in connection therewith, and to file the same
or cause the same to be filed with the Commission. Each of said attorneys shall
have full power and authority to do and perform in the name and on behalf of the
undersigned, in any and all capacities, every act whatsoever necessary or
desirable to be done to the premises, as fully and to all intents and purposes
as the undersigned might or could do in person, the undersigned hereby ratifying
and approving the acts of said attorneys and each of them.

     IN WITNESS WHEREOF, the undersigned has executed this instrument on this
7th day of May, 2002.



                                /s/ T. Kevin DeNicola
                                -----------------------------------------------
                                T. KEVIN DENICOLA
<PAGE>

                        LYONDELL CHEMICAL NEDERLAND, LTD.

                                POWER OF ATTORNEY

     WHEREAS, LYONDELL CHEMICAL NEDERLAND, LTD., a Delaware corporation (the
"Company"), a wholly owned subsidiary of Lyondell Chemical Company ("Lyondell"),
intends to file with the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), a Registration
Statement on Form S-3, including one or more prospectuses, with such amendment
or amendments thereto, whether pre-effective or post-effective, in each case as
may be necessary or appropriate, together with any and all exhibits and other
documents having relation to said Registration Statement (collectively, the
"Registration Statement"), in connection with potential future issuances of
securities registered thereby by Lyondell, the Company or their affiliate
co-registrants.

     NOW, THEREFORE, the undersigned, in his or her capacity as a director or
officer, or both, as the case may be, of the Company, does hereby appoint Kerry
A. Galvin and T. Kevin DeNicola and each of them severally, his or her true and
lawful attorneys or attorney with power to act with or without the others and
with full power of substitution and resubstitution, to execute in his or her
name, place and stead, in his or her capacity as a director or officer or both,
as the case may be, of the Company, the Registration Statement and all
instruments necessary or incidental in connection therewith, with such amendment
or amendments thereto in each case as may be necessary or appropriate, together
with any and all exhibits and other documents relating thereto as said attorneys
or any of them shall deem necessary or incidental in connection therewith, and
to file the same or cause the same to be filed with the Commission. Each of said
attorneys shall have full power and authority to do and perform in the name and
on behalf of the undersigned, in any and all capacities, every act whatsoever
necessary or desirable to be done to the premises, as fully and to all intents
and purposes as the undersigned might or could do in person, the undersigned
hereby ratifying and approving the acts of said attorneys and each of them.

     IN WITNESS WHEREOF, the undersigned has executed this instrument on this
7th day of May, 2002.

                                         /s/ Karen A. Twitchell
                                         ---------------------------------------
                                         KAREN A. TWITCHELL