Brownmillerite oxide Ca2Fe1.3Mn0.7O5+delta is synthesized and evaluated as a new cathode material for solid oxide fuel cells (SOFCs). The average thermal expansion coefficient (TEC) of Ca2Fe1.3Mn0.7O5+delta is 13.3 +/- 0.2 x 10(-6) K-1, close to that of the typical electrolyte materials. The lowest polarization resistance (Rp) (0.22 +/- 0.02 Omega cm(2) at 750 degrees C in air) and cathodic overpotential values are achieved when the material is sintered at 1000 degrees C on Ce0.9Gd0.1O1.95 (CGO) electrolyte. Two main oxygen reduction reaction (ORR) processes are identified. The rate limiting step for ORR is found to depend on the oxygen partial pressure. The excellent electrochemical performance indicates that Ca2Fe1.3Mn0.7O5+delta can be a promising cathode material for SOFCs. (C) 2013 Elsevier B.V. All rights reserved.