The microwave effect on barium strontium ferrate (BSF) was determined, and core-shell BSF-xCe cathode was co-fired with ceria-based electrolyte in a focused microwave cavity. The solubility of cerium (Ce) in BSF was up to x = 10 mol%. The grain size of the microwave sintered BSF was smaller. The conductivity of BSF-20Ce cathode with the lower transition temperature was significantly higher than that obtained by conventional sintering. The ohmic (R-ohm) and electrode polarization (R-p) resistances of the fuel cells were significantly reduced. The open-circuit voltage and peak power density of the microwave co-fired fuel cells increased with the Ce coatings. The high ionic conductivity at high operation temperature was due to the generation of more oxygen vacancies without clustering, caused by the effective absorption of microwave by the low valence iron oxide. Thus, the enhanced diffusion of Ce and the reduced R-p and R-ohm by the microwave energy improved the performance of fuel cells. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.