A composite cathode composed of NdBa0.5Sr0.3CO2.3Fe0.5O5+delta (NBSCF) and Ce0.9Gd0.1O1.95 (GDC) has been investigated to evaluate its electrochemical properties for intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on structural characteristics and oxygen redox stability. The composite cathode has a lower polarization loss than a pure NBSCF cathode because the specific addition of GDC provides extended electrochemically active sites where the oxygen reduction reaction (ORR) occurs. Accordingly, the optimized NBSCF-40GDC cathode material had the lowest ASR, 0.074 Omega cm(2) at 873 K, resulting in excellent cell performance of 1.83 W cm(-2) at 873 K. In particular, investigation into the oxygen redox stability reveals that the composite cathode has superior redox stability under the operating conditions than a bulk NBSCF cathode material, which affects the long-term stability of the cathode performance. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.