A product comprising a lower alkyl ester of a lower aliphatic carboxylic acid is produced by a process comprising reacting a lower alkyl ether with carbon monoxide in the presence of a catalyst comprising mordenite and/or ferrierite, optionally including an additional framework metal such as gallium, boron and/or iron, under substantially anhydrous conditions. More specifically, methyl acetate is selectively produced by reaction of dimethyl ether with carbon monoxide in the presence of a catalyst comprising mordenite or ferrierite, under substantially anhydrous conditions.