The acceptor-substituted BaSn0.875M0.125O3-delta (M = Sc, In, Y, and Gd) proton conductors were prepared by a wet chemical method. The effects of dopant nature on the structure, hydration energy and proton conduction have been investigated. Analysis of XRD data showed that all compounds present a cubic perovskite structure (space group: Pm <(3)overbar > m). Thermogravimetry analysis showed that the significant mass of water was gained in wet Ar during measurements, and the most negative hydration energy is observed for Sc-substituted BaSnO3 (-86 kj/mol). However, Y-substituted BaSnO3 exhibits the highest proton conductivity at low temperature under wet Ar, such as the total conductivity is 4.8 x 10(-4) S/cm at 600 degrees C. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.