The first part of this work describes the ozonization of low- and high-density polyethylene (LDPE and HDPE) using an ozone/air stream to create peroxide and hydroperoxide groups. These reactive groups were used to initiate the free-radical copolymerization reaction.The peroxide and hydroperoxide functions formed during ozonization were assayed by diphenyl picryl hydrazyl (DPPH).The other part of the work deals with the synthesis of graft copolymers by copolymerization of different monomers such as acrylic acid (AA), acrylonitrile (AN), chloromethylstyrene (CMS), 4-vinyl pyridine (4VP), acrylic acid-co-vinyl phosphonic acid (AA-co-AVP), acrylonitrile-co-vinyl phosphonic acid (AN-co-AVP) on ozonation-activated low-density polyethylene.The grafting reaction was carried out in bulk and in solution. The ozonized polyethylenes and corresponding graft copolymers were characterized by FTIR infrared spectroscopy and elemental analysis.