This work presents a simplified model of wide applicability for the determination of the pervaporation flux through hydrophilic membranes, provided that the adsorption isotherm of the permeating species onto the pervaporation membrane has a linear shape. The model predicts the pervaporation flux as a function of the activity of the penetrant in the liquid phase and the operation temperature. Experimental results obtained working with two polymeric membranes (CMC-CF-23 and Pervap 2256) applied to the dehydration of tetrahydrofuran (THF) and to the separation of methanol from alcohol-ether mixtures, respectively, have been satisfactorily correlated and the characterising parameters have been obtained. Furthermore, the model has been also tested against results obtained with two ceramic membranes, Pervap SMS and zeolite NaA, applied to the dehydration of ketonic mixtures and of tetrahydrofuran respectively. (c) 2005 Society of Chemical Industry.