Catalytic hydrogenation of unsaturated polyethers has been investigated. The partial reduction of the alkenyl functions appears a convenient way to prepare terpolymers from dipolymers. The free-radical crosslinking of the partially hydrogenated polyethers provides amorphous networks at room temperature. Ionic conductivity of the polymer electrolytes based on these networks is markedly increased, as compared to the nonhydrogenated ones. The electrochemical stability window of these electrolytes is retained. In addition, this process seems easy to scale up. The resulting terpolymers provide networks whose mechanical properties are appropriate for lithium polymer batteries.