Functionalization of the surface of polyethylene (PE) film with chitosan via gamma-ray irradiation technique followed by copper ion immobilization on this surface is proposed. The solubilization of chitosan in water by forming an organic salt with hydroxybenzyl triazole is a key factor in accomplishing the surface functionalization of PE with chitosan by gamma-ray irradiation. The chitosan induces the metal ion adsorptivity on PE film surface resulting in the successful copper ion immobilization. The work demonstrates an approach to convert a commodity polymer, such as PE, to a functional polymer with chitosan. (C) 2008 Elsevier Ltd. All rights reserved.