: As the permeate flux is one of the characteristic parameters in the pervaporative processes, and since the flux is directly proportional to the porosity of the support membrane, research on preparation of membranes with high porosity and suitable strength is quite important. For the purpose of improving the pervaporation performance especially for permeation flux of polymeric membranes, much effort has been devoted to fabricate the well-structured composite membrane comprising support layer. Polyethersulfone (PES) has been recently considered as a suitable material for support membrane due to its favorable mechanical strength, resistance to acids, and high thermal and chemical resistances. Flat- sheet membranes were prepared by phase inversion technique using poly(ethersulfone) (PES) dissolved in dimethylacetamide (DMAc) with and without adding poly(vinylpyrrolidone) (PVP 360000 ) or poly(ethyleneglycol) (PEG 400 ) in different concentrations and different temperature of coagulation bath(23 and 40 °C). The effect of the composition of the casting solution and coagulation temperature on membrane morphology and performance were investigated by porosity test, scanning electron microscoby images and pure water permeability. By varying polymer concentration in the casting solution, phase-inversion PES membranes with different structures and resistances were obtained as the support layers. Porosity was found to increase with decrease in casting solution concentration and increase in temperature of coagulation bath. The membrane prepared from 15 wt % PES with 3wt % PVP at 40 °C demonstrated better performance compared to the other compositions. With the increasing concentration of PES in the casting solution, the resistance of PES support layer would also increased and could dominate the pervaporation performance of the composite membranes. In this study, a series of composite poly(dimethylsiloxane) (PDMS)–poly(ethersulfone) membranes were prepared to investigate the influence of support layer structure on pervaporation and separation of mixture of toluene (representative of an industrially significant family of aromatic hydrocarbon chemicals produced from industrial wastes) from water. The influence of temperature, feed concentration, membrane thickness (based on wt% of PDMS in coating solution) and turbulency on the membrane separation efficiency, permeation behaviour and performance were systematically investigated. The permeation fluxes of both toluene and water were found to increase with increase in temperature and feed concentration. A near plateau value is obtained for water flux with further increase in concentration. It may be attributed to balance of plasticization and swelling effects (which could contribute to water flux increase) and water clustering effect (which could contribute to reduction in