A new A-site excessive strategy is reported to improve performance of layered perovskite cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). A new A-site excessive Gd1+x Ba1+xCo2O5+delta layered perovskite is investigated as cathode materials for IT-SOFCs. With an excess of A-site content, the crystal lattice and the thermal expansion coefficient increase slightly. The oxygen nonstoichiometry (d) increases, while the oxygen vacancy decreases by defect chemistry analysis. A-site excessive Gd1.05Ba1.05Co2O5+delta (GBC1.05) is well compatible with Gd0.2Ce0.8O2-delta at 1000 degrees C for 10 h. The electrical conductivity of GBC1.05 increases dramatically owing to the higher concentration of electron hole and the lower oxygen vacancy concentration. The electrochemical performance towards oxygen reduction reaction can be enhanced from 0.246 Omega cm(2) to 0.146 Omega cm(2) by introducing A-site excessive content of Gd and Ba. Consequently, GBC1.05 cathode exhibits a good cell performance of 830 mW cm (2) at 800 degrees C, indicating that A-site excessive Gd1.05Ba1.05Co2O5+delta layered perovskite is a potential cathode material for IT-SOFCs due to its high electrochemical performance. (C) 2017 Elsevier Ltd. All rights reserved.