A new approach for the development of lithium and proton conducting electrolyte membrane is here reported and discussed. Basically, the lithium polymer electrolyte is prepared by swelling a PVdF “precursor membrane” with a LiPF6 solution in EC–PC. Similarly, the proton polymer electrolytes are obtained by swelling a ceramic-added composite PVdF-based membrane in a H3PO4 aqueous solution. The results, even if in a preliminary stage, confirm that the membrane technology used for lithium can be extended to the proton case. The PVdF-based, acid-swelled membranes show high values of ionic conductivity and good thermal properties and thus, they appear of interest for practical applications, e.g. fuel cells.