Dense polymer membranes were made by mixing aqueous solutions of hydrophilic polymers poly( vinyl alcohol) ( PVA) and polyethyleneimine ( PEI) in different ratios for investigating the separation of Tetrahydrofuran (THF)/water azeotropic mixtures by pervaporation ( PV). In order to gain a more detailed picture of the molecular transport phenomenon, we have performed sorption gravimetric experiments at 30 degrees C to compute diffusion, swelling, sorption and permeability coefficients of PVA/PEI membranes in the presence of THF and water. The membranes were found to have good potential for breaking the azeotrope of THF at 6% concentration of water. An increase in PVA content in the blend caused a reduction in the flux and an increase in selectivity. Among the blends tested in the study, the 5: 1 PVA/ PEI blend membrane showed the highest separation factor of 181.5, exhibited a flux of 1.28 kg/ m(2)h for THF respectively at azeotropic feed composition.