The solid-state proton conductor, P 2 O 5 .5H 2 O, is found very difficult to handle due to presence of a very high content of moisture and corrosive nature. The addition of Al 2 O 3 and SiO 2 into P 2 O 5 .5H 2 O, forming composite electrolytes, obviates said drawback. The Zn+ZnSO 4 used as an anode to prepare cells with different cathode viz. I 2 , MnO 2 , PbO 2 , and V 6 O 13 characterized under different conditions. Open circuit voltage, discharge current and discharge time, on load voltage, discharge capacity, power density, and energy density are evaluated from discharge properties. Protonically conducting composite 70(P 2 O 5 .5H 2 O)/30 [(92SiO 2 )/08(Al 2 O 3 )] is found to be the optimum combination with the optimized 50Zn/50ZnSO 4 as anode and 40MnO 2 /60 graphite as cathode from secondary battery view point.