Water-ethanol sorption in strong sulfonated polystyrene cation-exchangers, in weak acrylic cation-exchangers and in neutral cross-linked dextran gels as well as their elastic properties have been measured. The effect of polymer matrix and cross-link density have been studied. The ionic resins were mainly in the Na+ form. The data have been analyzed by means of thermodynamic mixing models based on the Flory-Huggins equation, quasi-chemical UNIQUAC and non-random factor equations. The elasticity of the polymer networks was incorporated in the models as an additional free energy term and two elastic models derived for non-ideal networks were tested. The quasi-chemical approach using the non-random factors proved to be the best choice for calculating the mixing effects in the sorption equilibrium model. Experimental shear modulus data showed that the elastic properties of the ionic resins call be described adequately only by the model which takes into account the limited extensibility of the polymer chains. The elastic parameters estimated from the modulus data were used in the equilibrium model and a semi-quantitative correlation with the sorption data was obtained. Both the experimental data and modelling results indicated that the studied materials respond distinctly differently to the external solvent composition and have characteristic sorption properties. The polymer matrix type and ionic group density had clear effects on the phase transitions from gel-like to glassy polymer in different aqueous ethanol mixtures. Furthermore, the hydrophilicity and the water selectivity depended strongly on the polymer type. The acrylic acid resin was the most hydrophilic and had also the highest water selectivity. The water selectivity of the sulfonated PS-DVB resins and the dextran gels was approximately equal.