ZSM-5 zeolite-incorporated poly(dimethyl siloxane) membranes were prepared and molecular dispersion of zeolite in the membrane matrix was confirmed by scanning electron microscopy. After studying the behavior of membrane swelling at 30 C, the membranes were subjected to pervaporation separation of isopropanol-water mixtures at 30, 40 and 50 C. The effects of zeolite loading and feed composition on the pervaporation performances of the membranes were analyzed. Both permeation flux and selectivity increased simultaneously with increasing zeolite content in the membrane matrix. This was discussed on the basis of the enhancement of hydrophobicity, selective adsorption, and the establishment of molecular sieving action. The membrane containing the highest zeolite loading (30 mass%) exhibits the highest separation selectivity of 80.84 and flux of 6.78 x 10(-2) kg/m(2) h at 30 C for 5 mass% of isopropanol in the feed. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated. A pure membrane (M) exhibits higher E-p and E-D values compared to zeolite-incorporated membranes, signifying that permeation and diffusion require more energy for transport through a pure membrane, owing to its dense nature. Obviously, zeolite-incorporated membranes require less energy due to their molecular sieving action attributed to the presence of straight and sinusoidal channels in the framework of zeolite. All the zeolite-incorporated membranes exhibit positive OH, values, suggesting that the heat of sorption is dominated by the Henry's mode of sorption.