Proton conductivity of the P2O5-SiO2 glasses was investigated at sub-zero to 120°C. The glasses prepared by a sol-gel method are porous, pore diameters in which are smaller than 5 nm with an average diameter of 2.5 nm. The electrical conductivities, measured under 100%RH, follow the Arrhenius equation with the activation energy of 10 kJ/mol in the temperature between 120 and -20°C, Below -20°C, the adsorbed-water molecules are frozen to increase the activation energy and decrease the proton conductivity. We could conclude that our P2O5-SiO2 glasses, exhibiting high protonic conductivity of ∼30 mS/cm at 120°C, have potential for the electrolyte of the fuel cell operating at sub-zero to 120°C.