Pore structure and proton conductivities of several types of porous silica gels impregnated with H2SO4 have been studied. The amounts of impregnated H2SO4 increased with an increase in the pore volume of the silica gels, and with an increase in the concentration of H2SO4 used for the impregnation. The surfactant-templated mesoporous silica gels, which were impregnated with 5 M H2SO4, showed high conductivities in the order of 10(-1) S cm(-1) in a range from 40 to 80degreesC and 60% RH. Regularly ordered cylindrical pores with smaller pore diameter in the mesoporous silica gel were found to permit the retention of physisorbed water at high temperatures and thus high conductivities at temperatures around 100degreesC.