The sluggish activity of cathode at intermediate-temperature limits commercialization of proton-conducting solid oxide fuel cells (H-SOFCs). In this investigation, a novel cathode of Ba0.95Ca0.05Fe0.85Sn0.05Y0.1O2.9-delta F0.1 was successfully developed by co-doping of anion F and cations Ca, Sn, Y. We studied the effect of F--doping on phase structure, electrical conductivity and electrochemical properties of the cell. Compared with Ba0.95Ca0.05Fe0.85Sn0.05Y0.1O3-delta, F--doped Ba0.95Ca0.05Fe0.8Sn0.05Y0.1O3-delta exhibited higher conductivity. Composite cathode consisting of Ba0.95Ca0.05Fe0.85Sn0.05Y0.1.O3-delta F0.1 and Sm0.2Ce0.8O2-delta was applied in H-SOFCs with BaZr0.1Ce0.7Y0.2O3-delta electrolyte which achieves an encouraging performance with the maximum power density of 1050 mW cm(-2) and polarization resistance of 0.04 Omega cm(2) at 700 degrees C. The result of First-principles calculations based on spin-polarized Density Functional Theory shows that doping of F- reduces the activation energy required for migration of oxygen ions. These results demonstrate that the anions and cations co-doped strategy can provide a new horizon for the cathode in H-SOFCs. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.