Sorption and pervaporation experiments were carried out with cellulose triacetate membranes for the separation of methyl tert-butyl ether and methanol mixtures. The sorption experiments show that with an increase of MeOH concentration in the feed, the membrane swelling ratio increases first until a maximum value is reached and then remains constant. On the other hand, the MeOH concentration in the sorped phase first decreases to a minimum value and then increases with the transition occurring near the azeotropic point. In the pervaporation experiments, the total and MeOH permeation fluxes were found to increase with the increase of MeOH concentration in the feed while the MTBE permeation flux first increases and then decreases. The total permeation fluxes are significantly enhanced with an increase in temperature. This temperature dependence is more pronounced at low MeOH concentration, but the extent of increase of the total permeate flux is relatively constant when MeOH concentrations are greater than 10%, and it can be described by the Arrhenius law. Selectivity decreases with the increase of MeOH concentration and becomes more or less constant at high MeOH concentrations.