We develop a facile and effective top-down method for the fabrication of mesoporous Ba05Sr0.5Co0.8Fe0.2O3-delta (BSCF) oxide with a high specific surface area (similar to 25 m(2) g(-1)). The original BSCF is first synthesized by the simple EDTA citric acid complexing method, and then treated in H2O2 to obtain the mesoporous BSCF. The structure and morphology of as-prepared BSCF power is systematically characterized by N-2 adsorption/desorption isotherms, XRD, TEM, SEM and ICP techniques. A possible mechanism for the creation of mesoporous BSCF is proposed, in which Ba2+ and Sr2+ dissolve selectively from partial BSCF particles during the catalytic decomposition of H2O2. The electrochemical properties are investigated by the EIS and I-V test in the symmetrical cell and integrated single cell configurations, respectively. The interfacial reaction between BSCF electrode and YSZ electrolyte was suppressed successfully by using the BSCF with high specific surface area to decrease the sintering temperature (800 degrees C), thus the electrode exhibits high oxygen reduction reaction activity. The solid oxide fuel cell (SOFC) achieves an exciting peak power density of similar to 1800 mW cm(-2) at 800 degrees C, signifying the mesoporous BSCF, together with the preparation method, has a good application prospect in the development of SOFCs. (C) 2014 Elsevier B.V. All rights reserved.