A new class of inorganic-organic protonic polymer electrolyte was developed recently by grafting sulfonic and sulfonamide groups to the inorganic network by the sol-gel route. It associates the mechanical and thermal resistance of the silica backbone to the chemical reactivity induced by the organic chains grafted to the silica network. The organic chains are slightly acidic proton conductors bearing sulfonic and sulfonamide groups. The polycondensation of alkoxysilanes provides the inorganic silica backbone whereas the organic network is formed from reactive functional groups R＇ of alkoxysilanes of the type R＇Si(OR)(3), or by copolymerization of reactive organic monomers with functionalized alkoxysilanes. The synthesis of the resins is completed by organic crosslinking reactions (thermal or UV-curing). The transport of the protons through the solid could be described as a mechanism in which the proton was transferred from a donor (sulfonic group) to a suitable placed acceptor (e.g. sulfonamide group) in the case of a dry material. The conductivity was also studied as a function of relative humidity (r.h.) (wet proton conductors). Here, the proton transport could be described as a vehicular mechanism where the proton rides on a carrier molecule (H3O+). Furthermore the conductivity dependence on temperature follows a VTF behavior. By increasing the water content of the membranes up to 16 mass%, the conductivity increases from 10(-4) to 6 x 10(-2) S cm(-1) at 70 degrees C. These materials will be developed for thin film batteries. Their mechanical properties, thermal stability and glass transition temperature are discussed in connection with the conductivity results. (C) 2000 Elsevier Science Ltd. All rights reserved.