A novel single phase BaCe 0.5 Bi 0.5 O 3− δ (BCB) was employed as a cathode material for a proton-conducting solid oxide fuel cell (SOFC). The single cell, consisting of a BaZr 0.1 Ce 0.7 Y 0.2 O 3− δ (BZCY7)-NiO anode substrate, a BZCY7 anode functional layer, a BZCY7 electrolyte membrane and a BCB cathode layer, was assembled and tested from 600 to 700°C with humidified hydrogen (∼3% H 2 O) as the fuel and the static air as the oxidant. An open-circuit potential of 0.96V and a maximum power density of 321mWcm −2 were obtained for the single cell. A relatively low interfacial polarization resistance of 0.28Ωcm 2 at 700°C indicated that the BCB was a promising cathode material for proton-conducting SOFCs.