PROCESS FOR PRODUCING POLYMERIC ELECTROLYTE MEMBRANE

Disclosed is a method for producing a polymer electrolyte membrane, which comprises the steps of: removing a part of a salt component produced during polycondensation from a polymerization solution of a polymer electrolyte having a density of an ionic group of 2 mmol/g or more directly by centrifugal separation, thereby preparing a coating solution; applying the coating solution on a substrate by casting; removing a part of a solvent from the coating solution to forma film-shapedmaterial on the substrate; and bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove the salt component produced during the polycondensation. According to the method for producing an electrolyte membrane, even an electrolyte having a high density of an ionic group can be purified. Also disclosed is an electrolyte membrane capable of being used in a fuel cell which is operated at a high temperature higher than 80°C and under low humidity conditions having a relative humidity of 60% or less.