Vapor-phase carbonylation of methanol (MeOH) was investigated under atmospheric pressure. A novel heterogeneous Sn-Ni/C catalyst was utilized for the reaction. Experiments were designed with the elimination of mass-transfer resistances to extract reaction data. The data of primary reactions in the carbonylation were collected via a differential tubular reactor. Feed composition to the reactor was varied to examine the effect of partial pressures of reactants on the reaction rate. The carbonylation was conducted at several temperatures for the determination of activation energies. Power law rate models were employed to express the conversion of methanol and the yields of methyl acetate and dimethyl ether. Adequate results were obtained with the models to represent the experimental data.