A new membrane is developed, which is composed of highly crosslinked polydimethylsiloxane as the active layer on a support layer containing polyethersulfone and an appropriate additive (polyvinylpyrrolidone or polyethyleneglycol). The effect of porosity of the support layer on the performance of the fabricated membrane for pervaporative removal of toluene as a representative volatile organic compound from water is then studied. The support layer represents high porosity to improve the permeation rate of the composite membrane while it preserves the reasonable enrichment factor. It is shown that increasing in crosslinking time of the top layer decreases swelling degree of the membrane. The effects of operating parameters such as polymer concentration in the active layer, temperature. feed concentration, and stirring on the performance of pervaporative separation of toluene from water are evaluated. The results show that the enrichment factor is increased by increasing the polymer concentration in the top layer. The total activation energy and that for toluene are 29 and 0.22 kJ/mol, respectively. The increase in flux is retarded at high feed concentrations possibly due to a balance between cluster of water and the swelling effect. The membranes fabricated in the present study represent better pervaporative performances than those in literature. (C) 2011 Elsevier B.V. All rights reserved.