Vapor-phase carbonylation of methanol was investigated under atmospheric pressure on Ni/C and Sn-Ni/C catalysts. Sn-Ni/C was found as having a significantly higher activity than Ni/C in converting methanol and CO to methyl acetate and acetic acid. Product distributions of the two catalysts did not markedly differ from each other. Characterizing the catalysts by XRD demonstrated that Ni3Sn had formed on Sn-Ni/C. The adsorption of CO became substantially enhanced by the addition of Sn to Ni/C. This addition also resulted in a slightly higher CO adsorption strength.