Proton-conducting BaCeO3 membranes with different In-doping levels (from 10 to 30%) were fabricated on NiO-based anode substrates. Indium, which was only used as a trivalent element to create oxygen vacancies in BaCeO3 previously, was found to have the function of stabilizing BaCeO3 in this study. The In-doped BaCeO3 showed improved chemical stability against CO2, while even the traditional BaCeO3 substituting with a small amount of Zr decomposed in the same environment. Furthermore, unlike other strategies for stabilizing BaCeO3, the supported In-doped BaCeO3 membrane became dense after firing at relatively low temperatures. We also investigated the influences of the sintering temperatures and the In-doping levels on the densification and the electrical properties of the supported BaCeO3 membranes, which revealed that the In-doping strategy increased both the chemical stability and sinterability for BaCeO3 with little loss of electrical performance. (C) 2009 Elsevier B.V. All rights reserved.