Pr-deficient Pr1-xBaCo2O5+delta (P1-xBCO) oxides are evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Effects of Pr-deficiency on electrical conductivity, thermal expansion and electrochemical properties are investigated. Both the conductivity and thermal expansion coefficient (TEC) decrease with increasing Pr-deficiency. All of the conductivity, thermal expansion and TGA measurements demonstrate the existence of high temperature order-disorder transition. The oxygen reduction mechanism for P1-xBCO cathodes are characterized by electrochemical impedance spectroscopy. Over the temperature range of 600-800 degrees C, the cathode polarization resistance is mainly contributed from electronic charge transfer over the cathode surface. Proper Pr-deficiency reduces cathode polarization resistance (R-p), and the lowest R-p (0.081 Omega cm(2) at 700 degrees C) is obtained for the P0.92BCO cathode. In addition, the effects of order-disorder transition on the properties of P1-xBCO cathodes have also been discussed. Maximum power densities of a single-cell with P0.92BCO cathode on 300-mu m thick Sm0.2Ce0.8O1.9 (SDC) electrolyte achieve 446-987 mW cm (2) at 650-800 degrees C. These results suggest that, among various P1-xBCO oxides, P0.92BCO is the most promising candidate cathode material for IT-SOFCs. (C) 2016 Elsevier Ltd. All rights reserved.