The catalytic hydrolysis of chloromethane to methanol and dimethyl ether was studied over metal-exchanged zeolite Y (NaY, KY, CsY, MgY, CuY and FeY). All catalysts showed higher conversions than the blank reaction in the temperature range between 453 and 673 K. Methanol was the major product on all catalysts, with selectivity ranging from 76 to 95%. Dimethyl ether (DME) was the other major product formed with selectivity of 5-7% over alkaline cation-exchanged zeolite Y and 10-24% over the zeolites exchanged with polyvalent cations. The higher selectivity to DME over MgY, CuY and FeY is associated with the presence of stronger acid sites with respect to NaY. Theoretical calculations indicated that a mechanistic pathway involving methanolysis of an adsorbed methoxy group may account for the formation of dimethyl ether on alkaline cation-exchanged zeolites. (C) 2009 Elsevier B.V. All rights reserved.