The kinetics of methanethiol and dimethyl sulfide decomposition as well as the interaction of methanol with methanethiol and hydrogen sulfide on aluminium oxide catalysts have been studied. Some general regularities in the reaction mechanisms have been revealed. These reactions appear to proceed by surface methoxylation followed by interaction of CH3O groups with methanethiol or H2S molecules activated on the surface, resulting in the desired products. Kinetic models for the reactions on a nonuniform catalyst surface have been proposed.