A solid polymer electrolyte with a polyvinyl alcohol (PVA) matrix and a mixture of ethylene glycol (EG) and phosphoric acid as proton conductor has been developed. These complexes have been studied by X-ray diffraction (XRD), infrared Fourier transform spectrometry (FTIR) and electrochemical impedance spectrometry (EIS). The optimum ionic conductivity value of the ternary PVA-EG(45 wt%)-H3PO4(5 wt%) complex film has been achieved to be 5.2 10(-3)S cm(-1) at RH = 100% with adequate mechanical properties (especially flexibility) and with a low activation energy of 9 kJ mol(-1). Due to its good electrical and mechanical properties, this material has been successfully used as solid state proton electrolyte in Zn/MnO2 cell delivering a capacity of 220 Ah kg(-1) and an energy density of up to 286 Wh kg(-1).