Model approaches to phase equilibria in aqueous-organic electrolyte solutions are briefly reviewed, systems with chemical interactions being addressed specially. Semi-empirical models describing hydration and solvation processes in the salt and mixed-solvent systems are discussed. A model relating to aqueous-alcohol solutions with magnesium or calcium chloride that exhibit noticeable hydration and solvation effects is formulated. New versions of models for other types of systems characterized by strong specific interactions between electrolyte and organic component (acid-base interactions) are considered. The model performance is illustrated in cases of (1) vapour-liquid equilibrium in aqueous systems containing alkanolamine and such acid gases as carbon dioxide of hydrogen sulfide and (2) micellar solution-solid phase equilibrium in mixed aqueous solutions of alkylamine oxide and sodium dodecylsulfate at varying pH. (C) 2003 Elsevier Science Ltd. All rights reserved.