With only MoS2 as the anode catalyst, the performance of the solid oxide fuel cell (SOFC) using H2S-containing H-2 as fuel increased with temperature. The highest current density was 360 mA/cm(2) and the highest power density was 58 mW/cm(2) at 900 degrees C. When using pure H-2, the performance was slightly lower. Impedance measurements showed that both ohmic resistance and polar resistance increased in the absence of H2S. The performance of CoS-MoS2 as an anode catalyst was significantly better when compared with MoS2 alone. At 900 degrees C, the maximum current density when using CoS-MoS2 was 550 mA/cm(2) and the maximum power density was 100 mW/cm(2). The performance of all the metal sulfide catalysts was decreased immediately on introduction of CO to the feed gas. The effect was reversible, and performance recovered after removal of CO from the feed stream. This showed that the effect was due to strong adsorption of CO on the catalytic sites, and that the effect could be reversed through continued operation of the SOFC. When the supply of CO was discontinued, oxygen ions transferred from the YSZ membrane reacted with adsorbed CO to regenerate the active sites. (c) 2007 The Electrochemical Society.