Perovskite oxides Sm1-xBaxSr0.5Co0.8Fe0.2O3-delta(x = 0, 0.05, 0.10, 0.15, 0.20) have been synthesized by a citric acid method. The X-ray diffractometer results show that all samples exhibit a perovskite structure with orthorhombic symmetry. The X-ray diffractometer, Infrared spectroscopy and Raman spectroscopy results suggest an increase in the cell volume with Ba content. The X-ray Photoelectron spectra result suggests that the valence change of partial Co from 3+ to 4+ and the formation of oxygen vacancy are two mechanisms to satisfy charge neutrality when Sm3+ is partially substituted by Ba2+. The cathode polarization measurement of the symmetric cells with SBSCF cathodes shows that the area specific resistance decreases with the increase of Ba2+ substitution. The cathode with the composition x = 0.2 exhibits the lowest area specific resistance, which is 0.032 Omega cm(2) at 750 degrees C and 0.056 Omega cm(2) at 700 degrees C. The performance of Sm0.2Ce0.8O2-delta/Ni anode-supported cells using Sm1-xBaxSr0.5Co0.8Fe0.2O3-delta as cathode exhibits that the power density increase with increasing Ba2+ content. The cell with the composition x = 0.20 gives the maximum power density of 1030 mW cm(-2) at 650 degrees C and 285 mWcm(-2) at 500 degrees C. These results suggest that Ba2+ substituent substantially improves the electrochemical performance of Sm0.5Sr0.5Co0.8Fe0.2O3-delta, makes it a promising cathode material for intermediate temperature solid oxide fuel cells. (C) 2012 Elsevier B.V. All rights reserved.