In this paper strontium-site-deficient Sr2Fe2.4Co0.2Mo0.5O6-delta-based perovskite oxides (SXFCM) were prepared and evaluated as the cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). All samples exhibited a cubic phase structure and the lattice shrinked with increasing the Sr-deficiency as shown in XRD patterns. XPS results determined that the transition elements (Co/Fe/Mo) in SXFCM oxides were in a mixed valence state, demonstrating the small polaron hopping conductivity mechanism existed. Among the samples, S1.950FCM presented the lowest coefficient of thermal expansion of 15.62 x 10(-6) K-1, the highest conductivity value of 28 Omega cm(-1) at 500 degrees C, and the lowest interfacial polarization resistance of 0.093 Omega cm(2) at 800 degrees C, respectively. Furthermore, an anode-supported single cell with a S1.950FCM cathode was prepared, demonstrating a maximum power density of 1.16 W cm(-2) at 800 degrees C by using wet H-2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that the introduction of Sr-deficiency can dramatically improve the electrochemical performance of Sr2Fe1.4Co0.1Mo0.5O6-delta, showing great promise as a novel cathode candidate material for IT-SOFCs. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.