Membrane made from copolymer of acrylonitrile and methyl acrylate designated as PANMA was used for pervaporative dehydration of isopropyl alcohol (IPA) over the concentration range of 75-100 wt% IPA in water. Sorption of the membrane was evaluated in terms of thermodynamic interaction parameters based on Flory-Huggins lattice model. Engaged species induced clustering (ENSIC) model was also used to explain swelling of the membranes. Coupling in sorption was explained by activity coefficient of water and IPA in feed and membrane using Flory-Hugging thermodynamics and also by interpolating ENSIC parameters. Intrinsic membrane properties like partial permeability and membrane selectivity was also determined. Total solvent volume fraction (TSVF) model was used to determine diffusion coefficient and plasticization coefficient of the solvents. The membrane was found to show very high water selectivity (3540) and good flux (3.3 kg/m(2) h mu m) for highly concentrated (99.8 wt%) IPA at 30 degrees C temperature. (c) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.