Structural, physical and separation properties of polyurethane membrane were investigated by configuration bias grand canonical Monte Carlo and molecular dynamic methods and the effects of degree of polymerization on these properties were studied. To understand the effect of degree of polymerization of polyurethane membrane on its separation property, the adsorption of furfural as pure and binary mixture with water was studied for polyurethane membrane with varied degrees of polymerization from 5 to 100. The temperature range for simulation calculation was 298 K-360 K and the pressure range was 0-10 bar. Also the effects of feed composition, density and free volume of polyurethane membrane on its separation property were studied. It was found that the adsorption of furfural and water in polyurethane membrane depends on free volume of polyurethane and this dependency is more significant for the adsorption of water molecule. The results indicate that the maximum adsorption of furfural and water occurs on polyurethane membrane with polymerization degree of 10. (C) 2012 Elsevier Ltd. All rights reserved.