Temperature-programmed desorption (TPD) was used to study the adsorption and reaction of CH3SH and (CH3)(2)S-2 on the (0001) and (000 (1) over bar) surfaces of ZnO. The interaction of these molecules with ZnO was found to be structure-sensitive. Both CH3SH and (CH3)(2)S-2 adsorb dissociatively on ZnO(0001), forming adsorbed methylthiolate intermediates and only molecularly on ZnO(000 (1) over bar). In the case of CH3SH, this result is consistent with that reported previously for the interaction of Bronsted acids with ZnO and indicates that exposed cation-anion pairs are the active sites for dissociative adsorption. Only exposed Zn cations are required for the dissociative adsorption of (CH3)(2)S-2. Methylthiolate species produced by dissociative adsorption of CH3SH and (CH3)(2)S-2 on ZnO(0001) were found to undergo a variety of reaction pathways, including coupling to produce dimethyl sulfide and oxidation to formaldehyde, CO, and CO2. Pathways for the production of these various products are proposed.