Methanol carbonylation has been carried out over carbon supported sulfided CoMo catalysts without addition of CH3I, as promoter, to the feed. A temperature around 250 degrees C, and methanol concentrations higher than 5 mol% were found to be optimum for ester production. Sulfided Mo/C catalysts were inactive for methanol carbonylation, methane being the major product. While sulfided Co/C catalysts were as effective for ester production as CoMo/C catalysts, methanol conversion was higher in the latter. The selectivity to methyl acetate was found to be strongly dependent on the nature of the car bon support.