The methanation activity of unsupported and alumina supported nickel and nickel borides, prepared by sodium borohydride reduction, was determined during in situ exposure to 10 ppm H 2S at 525 K and 1.3 atm as a function of time. Using a recently developed deactivation model, deactivation rate constants and estimates of catalyst life were determined. The results indicate that nickel boride and Raney nickel catalysts are significantly more sulfur resistant, i.e. deactivate much more slowly in the presence of H 2S, compared to unsupported nickel and nickel alumina catalysts. The superior sulfur resistance of the boron and aluminium promoted catalysts is explained by (i) their intrinsically low deactivation rate constants and (ii) their large capacity for sulfur adsorption.