Anode-supported solid oxide fuel cells (SOFCs) based on complex-perovskite structured Ba3Ca1.18Nb1.82O9-delta (BCN18) proton-conducting electrolyte membranes have been successfully fabricated by a novel two-step co-sintering method. BCN18 has been reported to have excellent chemical stability against H2O and CO2, but is relatively difficult to densify. In this study, dense BCN18 electrolyte membranes with fine grain size have been obtained by a novel two-step co-sintering method at a relatively low sintering temperature of 1,300 degrees C, compared to the typical high sintering temperature of 1,550 degrees C. Furthermore, the Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-delta anode obtained by the novel two-step co-sintering method was composed of small particles with high porosity which is advantageous for electrode performance. Single fuel cells using BCN18 as the electrolyte, Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-delta as anode and Ba0.9Co0.7Fe0.2Nb0.1O3-delta as cathode demonstrated a power density of 106 mW cm(-2) at 750 degrees C, the best fuel cell performance ever reported for the BCN18 electrolyte. These results suggest that the two-step co-sintering method is a promising method to optimize the microstructure, and combined with proper electrodes, enhanced performance of anode-supported SOFCs using BCN18 proton-conducting electrolyte can be obtained. (C) 2012 Elsevier B.V. All rights reserved.