NOVELTY - A solid-state multi-layer proton-exchange membrane (20) comprises a metal foil plate (21), a voltage enhancement layer, and a metal oxide polymer layer. The voltage enhancement layer comprises a sub-micron-thick metal film having a large value of electron work function. The metal oxide polymer layer comprises two or more metals having different valences. Metal coating (I) (22) is provided adjacent to the metal oxide polymer layer, and metal coating (II) (23) is provided adjacent to the metal foil plate.    USE - For solid-state proton-exchange fuel cells (claimed) used for electric-power generation.    ADVANTAGE - The solid-state multi-layer proton-exchange membrane has high proton conductivity in temperature range of 300-500degreesC, by using very thin (less than 1 microns) metal oxide polymer films on a metal substrate by electrolytic anodizing of a metal alloy. The membrane allows for a significant increase in power density and efficiency and reduction in fuel cell cost per unit power. The metallic coatings operate as catalysts enhancing decomposition of hydrogen and oxygen molecules into atoms. Encapsulation of the protonic conductor between the metal substrate and the metal coating also preserves high proton concentration in the conductor at elevated temperatures.    DETAILED DESCRIPTION - A solid-state multi-layer proton-exchange membrane (20) comprises a metal foil plate (21) having hydrogen permeability, a voltage enhancement layer adjacent to the metal foil plate, and a metal oxide polymer layer adjacent to the voltage enhancement layer. The voltage enhancement layer comprises a sub-micron-thick metal film having a large value of electron work function. The metal oxide polymer layer comprises two or more metals having different valences. Metal coating (I) (22) is provided adjacent to the metal oxide polymer layer, and metal coating (II) is provided adjacent to the metal foil plate. An INDEPENDENT CLAIM is included for solid-state proton-exchange fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows the fuel cell.    Solid-state multi-layer proton-exchange membrane (20)    Metal foil plate (21)    Coating layers (22,23)    Gas diffusion layer (31)    External electrical circuit (40)