The high temperature proton conductors have attracted considerable interest for their potential application in gas sensors, hydrogen separators and fuel cells. Among various kinds of proton conducting materilas, rare earth doped barium cerate based ceramics display the highest conductivity, but their practical applications are limited because their well-recognized poor chemical stability against CO2 and/or H2O steam. In this work, F, Cl and Br doped BaCe0.90Gd0.1O3-delta (BCG) materials were prepared via a solid state reaction method with CuO as sintering aid to improve the materials chemical stability. The experimental results display that the added F, Cl or Br enters into the lattice of BCG without causing structure and morphology change. Halogen (F, Cl and Br) doping effectively enhances chemical stability of BCG in CO2 and H2O steam due to decreasing the materials basicity. Br doped BCG exhibits the best chemical stability as well as relatively high electrical conductivity. CuO addition reduces sintering temperature by 150 degrees C. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.