Ethyl acrylate (EA), Vinyl imidazole (VI), and their binary mixture have been copolymerized onto rayon in aqueous medium by mutual method using gamma-radiation. The graft yield has been determined as a function of different reaction parameters such as total dose, concentration of vinyl monomers, and amount of water. Effect of surfactant (1-octane sulfonic acid, sodium salt) has been studied on the percentage of grafting of EA, VI, and (EA + VI). A plausible mechanism has been suggested to explain the observed behavior of the surfactant on grafting. Water retention and moisture regain of the grafted film was determined at appropriate relative humidity. The graft copolymers have been characterized by IR spectroscopy and scanning electron microscopic methods. (C) 2008 Wiley Periodicals, Inc.