Offering fast oxygen reduction kinetics and high electrical conductivities relative to those of ABO(3)-type perovskite oxides, layered perovskite cathode materials have received considerable attention for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, we have investigated the effects of Ni substitution for the Co site in SmBa0.5Sr0.5Co2O5+delta in terms of structural characteristics, electrical properties, and electrochemical performance of smBa(0.5)Sr(0.5)CO(2-x)Ni(x)O(5+delta) (x = 0, 0.1, and 0.2) in relation to its application as an IT-SOFC cathode material. At the given temperature, the electrical conductivities of SmBa0.5Sr0.3Co2-x NixO5+delta (x = 0, 0.1, and 0.2) decrease with increasing Ni content. For x = 0.1, the lowest ASR value, 0.125 Omega cm(2), and the highest single cell performance, 1.78 W cm(-2) at 600 degrees C, are obtained. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.