Inorganic-organic composites were prepared by the sol-gel method using silicophosphate glass and a perfluorinated ion-exchange resin (Nafion). The effect of Nafion addition to silicophosphate glass on the morphology, thermal stability and electrical conductivity was examined. The as-prepared samples were amorphous and contained a large amount of water. The samples underwent crack propagation as they were heated in an ambient atmosphere. The samples comprised of silicophosphate glass and Nafion showed relatively superior thermal stability in comparison with Nafion. The electrical conductivity of the as-prepared composites was nearly the same as silicophosphate glass but smaller than Nafion. The composites retained larger electrical conductivities after they were heated at an elevated temperature.