in a method for producing a proton - conductive , structured electrolyte membrane , particularly for a fuel cell , a coating , which comprises at least one ion - conductive cross - linking component having at least one acid group and at least one photoactive substances interacting therewith , is applied onto a solid body surface . the coating is optically masked in that at least one region of the coating , in which the electrolyte membrane is supposed to be , is exposed such that the cross - linking component cross - links with the photoactive substances to form a polymer and / or copolymer network adhering to the solid body surface . at least one unexposed region of the coating is removed in order to structure the electrolyte membrane .