A-site Ba-deficient PrBa1-xCo2O5+delta (PB1-xCO, x = 0-0.08) oxides are synthesized and evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) with respect to crystal structure, chemical stability, thermal expansion behavior, electrical conduction and electrochemical performance. PB1-xCO with Ba-deficiency x = 0-0.08 has an orthorhombic structure, which shows lattice shrinkage with bigger x; higher Ba-deficiency x=0.1 causes formation of impurity phases. The PB1-xCO oxides are chemically stable with Gd0.1Ce0.9O1.95 (GDC) electrolyte at 1050 degrees C in air. Thermal expansion coefficient of PB1-xCO decreases slightly with higher Ba-deficiency. Electrical conductivity of PB1-xCO exhibits an initial decrease with higher Ba deficiency to x = 0.03 and then increases gradually to a maximum at x = 0.08. Introduction of Ba deficiency greatly improves electrochemical performance of PB1-xCO, characterized by decreased area specific resistances (ASRs) with higher Ba deficiency. The ASR values as low as 0.115 Omega cm(2) and 0.093 Omega cm(2) have been obtained at 600 degrees C in air for PB1-xCO with x = 0.05 and 0.08 respectively. These results have demonstrated that the Ba-deficient PB1-xCO (x = 0.03-0.08) oxides are promising cathode materials for IT-SOFCs. (C) 2012 Elsevier B.V. All rights reserved.