Ca-loaded activated carbon is developed as fuel for direct carbon solid oxide fuel cells (DC-SOFCs), operating without any carrier gas and liquid medium. Ca is loaded on activated carbon through impregnation technique in the form of CaO, which exhibits excellent catalytic activity and significantly promotes the output performance of DC-SOFCs. DC-SOFCs fueled by activated carbon with different Ca loading content (0, 1, 3, 5 and 7 wt. %) are tested and the performances are compared with the DC-SOFC running on the conventional Fe-loaded activated carbon. It is found that the performance of the DC-SOFC with 5 wt. % (373 mW cm(-2)) and 7 wt. % (378 mW cm(-2)) Ca-loaded activated carbon is significantly higher than that of the cells operated on 5 wt. % Fe-loaded activated carbon, 1 wt. % and 3 wt. % Ca-loaded activated carbon. The discharging time and fuel utilization of the DC-SOFC with 5 wt. % Ca-loaded activated carbon are also the optimal ones among all the cells. The microstructure, element distribution and carbon conversion rate of the Ca-loaded carbon, the impedance spectra of the corresponding DC-SOFCs are measured. The reasons for the reduced fuel utilization of 7 wt. % Ca-loaded carbon fuel are analyzed and the advantage of Ca-loaded carbon for DC-SOFCs is demonstrated in detail. (c) 2017 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.