Four types of hydrophilic zeolite membranes (A-type, Al-ZSM-5, mordenite, and Y-type) were used to dehydrate water/THF mixtures by pervaporation. At 303 K, the total fluxes increased with zeolite pore size, and membranes with lower Si/Al ratios had higher water/THF separation selectivities. The Y-type membrane, which was prepared using a template-free seeding technique, had the highest flux and selectivity; at 333 K, the total flux was 2.4 kg m(-2) h(-1) with a water/ THY selectivity of 290. The total flux increased with water feed concentration, but the selectivity decreased. Separation was based on both preferential adsorption of water and differences in diffusion rates. During continuous operation, the water permeate concentrations were higher than 95 wt %. Hydrophobic silicalite-1 and Ge-ZSM-5 membranes were used to remove THF from water. The Ge-ZSM-5 membrane had a total flux of 0.3 kg m(-2) h(-1) and a THF/water separation selectivity of 890 at 333 K for a 5 wt % THF aqueous solution.