SmBaCo1.7Ni0.3O5+delta-xSm(0.2)Ce(0.8)O(1.9) (SBCN-xSDC, x = 0-50 wt.%) composite cathodes were prepared and characterized for potential use in intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on an SDC electrolyte. The electrical conductivity and the thermal expansion coefficient (TEC) decreased with an increase in the SDC content of SBCN-xSDC composite cathodes. TEC values decreased from 15.59 x 10(-6) K-1 for SBCN to 13.17 x 10(-6) K-1 for SBCN-50SDC. Furthermore, the addition of SDC to the SBCN cathode improved its electrochemical performance. Among others, the SBCN-20SDC showed the lowest polarization resistance of 0.0272 Omega cm(2) at 800 degrees C; an anode-supported single-cell configuration of Ni-SDC/SDC/SBCN-20SDC obtained a maximum power density of 628 mW cm(-2) at 800 degrees C. Even when the content of SDC was raised up to 50 wt.%, the electrochemical performance of SBCN-SOSDC still exceeded that of pure SBCN. These results indicated that the SBCN-xSDC composite cathode is a promising material for ITSOFCs. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.