New polyethers have been prepared from polycondensation between several alpha,omega-dihydroxy(oxyethylene) and 3-chloro-2-chloromethyl-1-propene (CCMP). The CCMP units decrease both the crystallinity content and the melting point of the polyether chains. The free-radical polymerization of the dangling double bonds decreases the melting point of the crystalline phase and greatly enhances the mechanical strength of the network. The conductivity as well as the thermal behavior and the electrochemical stability of lithium electrolytes based on these networks have been investigated. Conductivity values close to 10(-5) S . cm-1 at 200-degrees-C were obtained for some salt concentrations without compromising the electrochemical stability. A transport number t+ = 0.46 has been determined for LiTFSI/network complexes.