Utilization of membrane offers the promise of huge energy savings if successfully applied to petroleum separations. Membranes are bound to enter into refining petroleum operations involving liquid separations once appropriate materials and modules are developed. Hybrid processes such as utilizing membrane modules to azeotropes formed during distillation are particularly attractive because they can offer less process complexity and reduced capital investment. A pervaporation performance was studied using pervaporation through the polymer blendmembranes for the separation of benzene and cyclohexane mixtures to investigate the relationship between pervaporation performance and polymer blend design. Solubility parameter calculation and thermodynamic calculation were used to predict the pervaporation performance for the benzene and cyclohexane mixture system using polymeric blend membrane composed of NBR, PVC and polar copolymers with various solubility parameters. The solubility parameter of the polymer blend membranes were controlled with different blend ratio. Screening of the membranes was accomplished by simple swelling experiments. Selectivity for the polar component increased with increasing NBR and PVC contents. Solubility parameter from polar and hydrogen bonding properties and activity calculated from thermodynamic model predicted the trend of swelling characteristics and pervaporation performance. Solubility parameter and thermodynamic calculation provide an a priori methodology for seeking the best blend formulations.