Graft copolymerization induced by gamma radiation has being used as a tool to modify the surface properties of a range of polymeric substrates. This work describes the use of this technique for the grafting of 2-hydroxyethyl methacrylate (HEMA) branches onto low-density polyethylene (LDPE) surface, in order to improve its hydrophilic properties. Sample preparation protocols were selected from previous work in order to obtain films with high grafting yields. The obtained PE-g-HEMA films were characterized by thermal analysis techniques (DSC and TGA), and by Fourier transform infrared spectroscopy (FTIR). The results obtained show that, upon irradiation, there is some loss of cristalinity of the copolymer backbone, but also that the samples keep a good thermal stability. The water uptake of the samples was evaluated. Hydration levels up to near 95 % with a ydration/dehydration average ratio of 1:5 were obtained.