A single phase new proton conductive electrolyte of CeP2O7 was synthesized. The electrical conductivity was measured in the temperature range of 50-250 degrees C under different atmospheres, and the conductivity of CeP2O7 increased with the increasing of temperature and kept above 10(-2) S/cm in the temperature range of 150-250 degrees C. Proton transport numbers of this material under various conditions were estimated based on the ratio of the electromotive force to the theoretical value. And the mechanism of proton conductivity under various conditions was also discussed. A single H-2/O-2 fuel cell with CeP2O7 as electrolyte membrane exhibited a reasonable power density of 25 mW/cm(2) at 200 degrees C, showing potential applications. (c) 2008 Elsevier B.V. All rights reserved.