A novel fast proton-conducting silicophosphate-HClO4 (SiP-HClO4) gel glass and SiP-HClO4-alumina composite are successfully fabricated. The fabricated inorganic composites show good thermal stability and stable conductivity up to 140 degreesC, which indicates a high proton conductivity of over 2.6 x 10(-2) S cm(-1). The high conductivity of the composites is attributed to the fast proton-conducting property of the three-dimensional SiP-HClO4 gel glass network which contains both trapped acid ions (ClO4-) as a proton donor and strongly hydrogen-bonded hydroxyl groups combined to P-O-Si bonds as proton conduction paths. (C) 2004 Published by Elsevier B.V.