The proton conducting behavior of various TiO2-ZnO-P2O5 systems such as zinc-doped titanium pyrophosphate (Ti1-xZnxP2O7), phosphorous oxide-excess non-stoichiometric Ti1-xZnxP2O7 and composites of ZnO-P2O5 glass in a TiP2O7 powder matrix was examined at intermediate temperatures between 100 degrees C and 250 degrees C under dry and humid conditions. The electrical conductivity of Ti1-xZnxP2O7 was relatively low (< 10(-5) S cm(-1)) while that of phosphorous oxide-excess Ti1-xZnxP2O7 was high (> 10(-3) S cm(-1)). In the latter case, the ZnO-P2O5 glass layer that formed on the surface of the TiP2O7 core may contribute to its high conductivity. To elucidate it further, we prepared ZnO-P2O5 glass-TiP2O7 powder composites and investigated their characteristics on proton transport. The results suggested that a ZnO-P2O5-derived hydrogel formed on the surface of TiP2O7 in the humid atmosphere which led to its high conductivity. We also found that the volume ratio of the TiP2O7 particles in the composite influenced the conductivity, i.e., the maximum value of conductivity was observed at certain volume ratio of TiP2O7. This conductivity enhancement is hypothesized to be related with the formation of a highly proton-conducting interfacial layer between the ZnO-P2O5-derived hydrogel and TiP2O7. Based on the idea, a physicochemical model is applied to describe the characteristics on proton transport. Such glass hydrogel-polycrystalline composite can provide the strategy for the fabrication of fast ion conducting materials working at the intermediate temperature. (C) 2011 Elsevier B.V. All rights reserved.