LYONDELL AND MILLENNIUM COMBINE OLEFINS AND POLYMERS BUSINESSES
                   TO CREATE NEW $5 BILLION CHEMICAL COMPANY

Jointly-Owned Venture Expected to Improve Annual Profitability by $150 Million
and Reduce Effects of Industry Cyclicality on its Parent Companies

     Houston,  TX,  Iselin,  NJ and  London,  England--July  28,  1997--Lyondell
Petrochemical  Company  (NYSE:LYO)and  Millennium Chemicals Inc. (NYSE:MCH) have
signed a definitive  agreement to form a new venture,  with expected revenues of
approximately  $5 billion,  comprised  primarily  of the  olefins  and  polymers
businesses of the two companies.

     The new  company is expected  to be the  largest  producer of ethylene  and
polyethylene in North America. It will consist of 13 manufacturing facilities on
the U.S.  Gulf Coast and in the U.S.  Midwest,  producing  ethylene,  propylene,
polyethylene,   polypropylene,   ethyl  alcohol  and  associated  products.  The
combination   will  create  a  strong  financial  entity  with  book  assets  of
approximately  $5 billion.  it plans to have $1.745 billion of debt,  witha note
receivable from Lyondell of $345 million,  and  substantial  free cash flow. 

     The new venture company,  which will be operated as a partnership,  will be
owned 57% by Lyondell and 43% by Millennium.  The venture's governance structure
will include a six-person committee,  co-chaired by Dan F. Smith,  President and
Chief Executive Officer of Lyondell, and William M. Landuyt,  Chairman and Chief
Executive  Officer  of  Millennium.  Smith  also will  serve as Chief  Executive
Officer of the venture company, which will be headquaretered in Houston, Texas.

The Venture  Creates Value Through Cost  Reductions,  Operating  Efficiency
Improvements and Broader Product Mix 

     "We will create a new world class  chemical  company  with  enhanced  asset
utilization  and a leading  cost  position  across a broad line of  products  by
blending  assets,  employees  and operating  capabilities  from  Millennium  and
Lyondell," said Dan F. Smith.  "The  extraordinary  fit of these businesses will
provide  higher  earnings  power and create  unique value that we expect will be
differential in the industry."

     "The venture will have one of the broadest  product  lines in the industry,
with  extensive  product  development  and  research  capabilities  and the best
employees  from each  organization,  enabling it to better  serve  customers  in
rapidly growing markets," said William M. Landuyt.

     The  partnership  is expected to generate  more than $150 million in annual
pre-tax  profit  improvement.  Substantial  savings are  expected to be realized
early,  with the full $150 million annual  savings  achieved by the end of 1999.

     Cost improvements  will be achieved in such areas as eliminating  duplicate
overhead and staffing, improved purchasing capabilities,  and better utilization
of existing logistics and distribution channels.

     Efficiency improvements will include such items as greater use of feedstock
flexibility,  expanding  the upgrade of  co-products  internally,  sharing  best
business practices, and optimizing production scheduling of polymer plants.

     Customers will benefit from the greater supply  flexibility  gained through
multiple  olefins  production  sites and polymers  customers will have access to
significantly broader resin product lines.

     "This  transaction is a major step in the execution of Lyondell's  strategy
to reduce  cyclicality  and grow the  petrochemicals  business  through  greater
integration and a broader  downstream product mix. It also advances our low cost
strategy  by  compounding  the  benefits of recent  cost  reduction  efforts and
building a base for future  improvements.  Increased cash flow generated by this
venture,  as well as our  interest  in  LYONDELL-CITGO  Refining  Company,  will
provide  Lyondell  with a greater  number of cash  allocation  options to create
shareholder  value than ever before in our history,"  said Smith. 

     Landuyt said,  "This  combination  helps fulfill  Millennium's  strategy to
maximize value  creationin our  polyethylene  and related  businesses by driving
down costs and by partnering  with an  organization  that shares our  relentless
focus on optimizing  synergistic  opportunities.  The transaction  also enhances
Millennium's  financial  flexibility to pursue  expansion of our specialties and
intermediates businesses thereby reducing the volatility of Millennium's overall
business portfolio."

Closing Expected this Year
     
     The  transaction,  which has been  unanimously  approved  by the  Boards of
Directors  of both  companies,  is  expected  to  close by year  end,  following
approval by both  companies'  stockholders  and  satisfaction  of certain  other
conditions.

The Venture Will Be Comprised of Quality People, Assets & Operating Capabilities

     Lyondell's  contribution to the new venture company includes the businesses
associated with the following operations:

     The olefins  business,  comprised of two olefins plants at the  Channelview
Petrochemical  Complex near Houston,  TX, with annual  capacities of 3.8 billion
pounds of ethylene and 2.2 billion pounds of propylene,  and related  facilities
for  the   manufacture   and  production  of  butadiene,   aromatics  and  other
co-products, as well as storage facilities at Mont Belview, TX.

     The polymers business, consisting of three manufacturing facilities located
in Pasadena,  Victoria and  Matagorda  County,  TX, with annual  capacities of 2
billion pounds of polymer resins.

     The technology  group and certain  business  functions  located in and near
Houston.

     The venture will assume primary responsibility for $745 million of existing
Lyondell  company  debt;  Lyondell  also will  remain  liable on this  debt.  In
addition, Lyondell will provide a $345 million note payable to the venture.

     Not included in the venture are Lyondell's  58% interest in  Lyondell-CITGO
Refining,  Ltd. (LCR) and its 75% interest in Lyondell Methanol (a joint venture
with MCN Investment Corp.).

     Millennium's   contribution  to  the  new  venture  company   includes  the
businesses  associated  with the  following  operations:  

     The olefins business  comprised of olefins plants at Clinton,  IA, LaPorte,
TX, and Morris, IL, with a total capacity of 3.8 billion pounds of ethylene.

     The polymers business  comprised of 4.8 billion pounds of polymers capacity
comprised of five manufacturing  facilities in Clinton, IA; Morris, IL; LaPorte,
Port Arthur and Chocolate Bayou, TX.

     The performance polymers business with manufacturing facilities in Tuscola,
IL; Fairport Harbor and Heath, OH; and Crockett,  TX. The synthetic  ethanol and
ethyl ether businesses with facilities at Tuscola,  IL; Newark, NJ; and Anaheim,
CA.

     Research and technology groups and a research center in Cincinnati, OH.

See list of plants and  capacities in Attachment I. 

     Millennium will receive $1 billion from the exchange:  The partnership will
assume $750 million of Millennium's inter-copany debt, which will be repaid from
the  proceeds of new bank debt to be arranged by the  partnership.  In addition,
Millennium will retain $250 million of accounts  receivable form the contributed
business.

     Not included in the venture are Millennium's interest in acetic acid, vinyl
acetate and methanol assets and  operations.  Also excluded from the transaction
are  Millennium  Inorganic  Chemicals,   Millennium  Specialty  Chemicals,   and
Millennium's equity interest in Suburban Propane Partners.

Executive Management Team Announced for New Venture
 
     The venture company will be governed by an owners'  committee  comprised of
representatives  of Millennium  and Lyondell.  Members of the owners'  committee
will include:

Dan F. Smith, President and CEO of Lyondell Petrochemical Company and CEO of the
venture -  Co-Chairman 
William M. Landuyt,  Chairman and CEO of Millennium  Chemicals Inc.- Co-Chairman
Dr.  Ronald H. Yocum,  President  and CEO of  Millennium  Petrochemicals  Inc. -
Member  
John E. Lushefski,  Senior Vice President and CFO of Millennium Chemicals Inc. -
Member
Jeffrey R. Pendergraft,  Senior Vice President,  Chief Administrative Officer of
Lyondell Petrochemical Company - Member 
Clifton B.  Currin,  Jr.,  Vice  President,  Corporate  Development  of Lyondell
Petrochemical Company - Member

     The  members  of the  executive  management  team  of the  venture  company
include: 

Eugene R. Allspach, President and Chief Operating Officer
Joseph M. Putz, Senior Vice President, Finance and Administration
Debra L. Starnes, Senior Vice President, Polyolefins
John R. Beard, Vice President, Manufacturing
J. R. Fontenot, Vice President, Engineering
Alan Houlton, Vice President, Customer Services
Gerald A. O'Brien, Vice President, Secretary
Myra J. Perkinson, Vice President, Human Resources
W. Norman Phillips, Jr., Vice President, Olefins
Kerry F. Williams, Vice President, Research and Development
Jeffrey L. Hemmer, Director, Business Process Improvement

     Lyondell  Petrochemical  Company  (web site:  www.lyondell.com)  is a major
commodity  petrochemical and polymers company with headquarters in Houston,  TX.
The company  manufactures and markets olefins  (primarily  ethylene,  propylene,
butadiene, butylenes and specialty products),  aromatics, methanol and MTBE, and
polymers (or polyolefins),  including high-density  polyethylene,  polypropylene
and low-density polyethylene. Lyondell is involved in petroleum refining through
its 58%  participation  interest in  LYONDELL-CITGO  Refining Company Ltd (LCR),
which produces refined petroleum products, including gasoline, low sulfur diesel
and jet fuel.  Lyondell  operates  a  methanol  business,  in which it has a 75%
ownership interest.

     Millennium  Chemicals  Inc. (web site:  www.millenniumchem.com)  is a major
international  chemical company,  with leading market positions in a broad range
of  commodity,  industrial,  performance  and  specialty  chemicals.  Millennium
Chemicals  was formed as a result of a  spin-off  from  Hanson  PLC, a UK public
company, on October 1, 1996.

Millennium Chemicals Inc. is

      the largest producer of polyethylene products in the United States;
      the second  largest  producer  of titanium  dioxide  (TiO2 ) in the United
      States and the  third-largest in the world; the second largest producer of
      acetic  acid and vinyl  acetate  monomer in the United  States;  a leading
      producer of high value-added performance polymers,  color concentrates and
      polymeric powders and other products, including titanium tetrachloride, 
          cadmium/selenium pigments and silica gel;
      and a leading producer of fragrance and flavor chemicals.

The statements in this release relating to matters that are not historical facts
are forward-looking statements that involve risks and uncertainties,  including,
but not limited to,  future global  economic  conditions,  production  capacity,
competitive  products and prices and other risks and  uncertainties  detailed in
the companies' Securities and Exchange Commission filings.

For inquiries, please call:
Lyondell                                           Millennium Chemicals
Media: Jackie Wilson (713) 652-4596 or             Investors and Media:
David Harpole (713) 652-4125                       Mickey Foster (732) 603-6777
Investors: Kevin DeNicola (713) 652-4590








                     MANUFACTURING OPERATIONS OF THE VENTURE

                                                                       

Location                             Principal products                  Annual capacity

Channelview, Texas                   Ethylene                            3.8 billion pounds
                                     Propylene                           2.2 billion pounds
                                     Butadiene                           615 million pounds
                                     Benzene                             90 million gallons
                                     Toluene                             40 million gallons
                                     Dicyclopentadiene (DCPD)            80 million pounds
                                     Isoprene                            108 million pounds
                                     Resin oil                           120 million pounds
                                     Piperylenes                         100 million pounds                    
                                     Alkylate                            22,000 barrels per day
                                     MTBE                                13,000 barrels per day

Chocolate Bayou, Texas               High -density polyethylene          400 million pounds

Crockett, Texas                      Wire & cable compounds, color       120 million pounds
                                     and  additive concentrates

LaPorte, Texas                       Ethylene                            1.74 billion pounds
                                     Low-density polyethylene            395 million pounds
                                     Linear-low density polyethylene     480 million pounds
                                     High-density polyethylene           545 million pounds

Matagorda County, Texas              High-density polyethylene           1,050 million pounds

Pasadena, Texas (Bayport plant)      Polypropylene                       400 million pounds
                                     Low-density polyethylene            140 million pounds

Port Arthur, Texas                   Low-density polyethylene            190 million pounds
                                     High-density polyethylene           540 million pounds

Victoria, Texas                      High-density polyethylene           450 million pounds

Morris, Illinois                     Ethylene                            1.13 billion pounds
                                     Low-density polyethylene            540 million pounds
                                     Linear low density polyethylene     650 million pounds
                                     Polypropylene                       280 million pounds

Tuscola, Illinois                    Ethyl alcohol                       50 million gallons
                                     Diethyl ether                       5 million gallons
                                     Compounds for wire & cable          36 million pounds
                                     Microfine polyolefin powders        10 million pounds      

Clinton, Iowa                        Ethylene                            960 million pounds
                                     Low-density polyethylene            430 million pounds
                                     High-density polyethylene           450 million pounds
                                     
Fairport Harbor, Ohio                Wire & cable compounds, color       60 million pounds
                                     concentrates

Heath, Ohio                          Color, additive and foam            39 million pounds
                                     concentrates, performance
                                     compounds