Phase structure, structure stability, electrical properties and catalytic activity for oxygen reduction reaction of the Ba-deficient layered-perovskite oxides LaBa1-xCo2O5+delta (LB1-xCO, x = 0.00-0.15) have been studied to determine their viability as cathode material of intermediate-temperature solid oxide fuel cells (IT-SOFCs). LB1-xCO had tetragonal layered-perovskite structure when calcined at 850 degrees C-1050 degrees C in air but transformed into cubic structure at higher temperatures. The LB1-xCO oxide exhibited lower electrical conductivities and decreased area-specific resistances (ASRs) on the Ce0.9Gd0.1O1.95 (GDC) electrolyte with higher Ba-deficiency content. Among the samples, the LB0.90CO (x = 0.10) oxide exhibited the best electrochemical performance with ASR values of 0.118 Omega cm(2) at 600 degrees C and 0.023 Omega cm(2) at 700 degrees C respectively, similar to 40% lower than the results of the parent oxide (x = 0), demonstrating its promising application as cathode materials of IT-SOFCs. (C) 2013 Elsevier B.V. All rights reserved.