This disclosure is directed to polymer membranes to be used in electrochemical cells and improved processes for producing the same. The membranes are produced by radiation grafting techniques. The improved process includes the grafting of a hydrophilic monomer, such as methacrylic acid in a chlorinated organic solvent onto an inert base film such as polyethylene. The process also includes but is not limited to the use of inhibitors to limit homopolymerization of a grafting material, as well as emulsifying agents to lower the electrolytic resistance of the finished membrane.