Novel proton conductor BaCe0.7In0.2Yb0.1O3-delta (BCIYb) has been successfully synthesized by a modified Pechini method and characterized as electrolyte for intermediate temperature solid oxide fuel cells. Acceptable tolerance to wet CO2 environment was found during chemical stability tests. No interaction between the BCIYb electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) cathode was observed during the cathode fabrication process. Further, no detectable impurity phase was found when the BCIYb-LSCF mixed powders were calcined at 700 degrees C for 50 h. BCIYb dense samples sintered at 1450 degrees C for 5 h showed acceptable conductivities of 7.2 x 10(-3), 8 x 10(-3), 4.5 x 10(-3) and 3.1 x 10(-3) S cm(-1) at 800 degrees C in dry air, wet air, wet H-2 and wet N-2, respectively. The maximum cell power outputs of single cells with the configuration of Ni-BaZr0.1Ce0.7Y0.2O3-delta (BZCY)|BCIYb|BZCY-LSCF were 0.15, 0.218 and 0.28 W cm(-2) at 600, 650 and 700 degrees C, respectively. No cell degradation was observed for cells operated at a constant voltage of 0.7 V in the 25 h short-term durability test. (C) 2011 Elsevier B.V. All rights reserved.