NOVELTY - A multilayered composite membrane (10) has carrier film (12), layer(s) (14) of an undoped conductive polymer electrolyte material, and layer(s) (16) of a doped conductive polymer electrolyte material. Each layer of undoped conductive polymer electrolyte material has a dry thickness of 5-20 microns. Each layer of doped conductive polymer electrolyte material has a dry thickness of 5-20 microns, and is doped with nanoparticles (18). The nanoparticles comprise 0.1-100 wt.% of conductive polymer electrolyte material based on the dry weight of layer(s).    USE - Multilayered composite membrane is used in membrane electrode assemblies of fuel cells, such as hydrogen or methanol fuel cells, used as portable power supply in automobile applications and stationary power generation.    ADVANTAGE - The multilayered composite membrane has excellent mechanical strength, economical efficiency, durability, chemical stability, gas permeability, high-temperature resistance, dimensional stability, crack resistance, crease resistance, conductivity over a wide range of relative humidity, swelling resistance, and water management, and longer operating times. Methanol crossover and other gas crossover are reduced by the zirconium-rich polymer layers where the in-plane oriented inorganic nanoparticles serve as a barrier to the permeating gases. The membrane provides fuel cells having excellent performance characteristics. Anode hydration by back diffusion of water is improved.    DETAILED DESCRIPTION - A multilayered composite membrane comprises a carrier film for supporting the balance of multilayered composite membrane, layer(s) of an undoped conductive polymer electrolyte material adjacent to the carrier film, and layer(s) of a doped conductive polymer electrolyte material adjacent to respective layer(s) of conductive polymer electrolyte material. Each layer of undoped conductive polymer electrolyte material has a dry thickness of 5-20 microns. Each layer of doped conductive polymer electrolyte material has a dry thickness of 5-20 microns, and is doped with nanoparticles. The nanoparticles comprise 0.1-100 wt.% of conductive polymer electrolyte material based on the dry weight of layer(s). The nanoparticles comprise zirconium, zirconium oxides, clays, zeolites, silica, silicon, compounds of silica, and/or compounds of silicon. An INDEPENDENT CLAIM is included for production of multilayered composite membrane.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of the multilayered composite membrane.    Multilayered composite membrane (10)    Carrier film (12)    Undoped electrolyte material layer (14)    Doped conductive polymer electrolyte material layer (16)    Nanoparticles (18)