Solid oxide fuel cells (SOFCs)with the construction of Ni-BaCe0.8Gd0.2O2.9 (BCGO)BCGO/La0.5Sr0.5CoO3-delta (LSCO)-BCGO are reported. With commercial liquefied ammonia directly used as the fuel, the performance of a single cell was tested from 600 to 750 degrees C. The OCV was 1.102 and 0.985 V at 600 and 700 degrees C, respectively, which is fairly consistent with the theoretical values calculated on the assumption of ammonia completely decomposing. Also a useful power density was achieved; the maximum power density was 355 mW cm(-2) at 700 degrees C. For comparison, cells were also tested with hydrogen as the fuel and CO2-free air as the oxidant at 700 degrees C, where the power density was about 371 or 324 mW cm(-2). The performance of the cells tested under various conditions implied that ammonia might be a good fuel for a SOFC. (c) 2006 Elsevier B.V. All rights reserved.