Abstract: A totally solid polymer electrolyte composition with high ionic conductivity and enhanced mechanical properties is provided. This electrolyte composition is produced by polymerizing a monomer composition comprising a molten quaternary ammonium salt having a polymerizable functional group introduced therein and a charge transfer ion source in the presence of a polymeric reinforcing material. The polymeric reinforcing material can be formed into a composite of polymer blend morphology by dissolving the monomer composition and the reinforcing material in an appropriate organic solvent and polymerizing the solution. Alternatively, the composite can be obtained by impregnating a porous sheet or film as the reinforcing material with the monomer composition and effecting polymerization.