Surface science models of silica- and alumina-supported CoMoS catalysts have been made by impregnating thin SiO2 and Al2O3 films with a solution of nitrilotriacetic acid (NTA) complexes of cobalt and molybdenum. XPS spectra indicate that the order in which cobalt and molybdenum transfer to the sulfided state is reversed with respect to oxidic Co and Mo systems prepared by conventional methods, implying that NTA complexation retards the sulfidation of cobalt to temperatures where MoS2 is already formed. Catalytic tests show that the CoMoS model catalysts exhibit activities for thiophene desulfurization and product distributions similar to those of their high surface area counterparts.