Radiation-induced graft copolymerization has been used extensively to modify polymers with acrylic acid to impart some properties of the monomer but still maintain the strength and stability of the polymer chain. This article describes the process of the simultaneous graft copolymerization reaction for the modification of hydrocarbon- and fluorine-containing polymers to produce hydrophilic membranes. The effects of the conditions of grafting, such as the radiation dose rate, the total dose, and the monomer concentration on the resulting graft copolymers are discussed in detail. The characterization of the grafted membranes is described in terms of their composition, ionexchange capacity, equilibrium water content, and electrolytic resistivity. It has been shown that some of these properties can be predicted from the degree of grafting.