Double-proveskite YBa0.5Sr0.5Co2O5+delta (YBSC) was investigated as potential cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). YBSC material exhibited a good chemical compatibility with the La0.9Sr0.1Ga0.8Mg0.115Co0.085O2.85 (LSGMC) electrolyte up to 950 degrees C for 2 h. The substitution of Sr for Ba significantly enhanced the electrical conductivity of the YBSC sample compared to undoped YBaCo2O5+delta, and also slightly increased the thermal expansion coefficient. At 325 degrees C a semiconductor-metal transition was observed and the maximum electrical conductivity of YBSC was 668 S cm(-1). The maximum power densities of the electrolyte-supported single cell with YBSC cathode achieved 650 and 468 mW cm(-2) at 850 and 800 degrees C, respectively. Preliminary results suggested that YBSC could be considered as a candidate cathode material for application in IT-SOFCs. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.