Experimental data on sulfur's impact on solid oxide fuel cell (SOFC) nickel anodes have been analyzed using an isotherm for the sulfur coverage on the Ni surface: theta(S)=1.45-9.53x10(-5)T+4.17x10(-5)T ln Y, where Y is the ratio between the partial pressures of hydrogen sulfide and hydrogen. The loss of performance, P-l, of the SOFC can be correlated by P-l=k(*)(theta(S)-theta(min)), where theta(min)>0 depends on the current density and anode material. The data range covered is 700-1000 degrees C, concentration of hydrogen sulfide 0.05-50 ppm. (C) 2008 The Electrochemical Society.