(Liquid-liquid) equilibrium (LLE) data of the solubility curves and tie-line compositions have been determined for mixtures of (water + acetic acid + organic solvent (o-xylene, m-xylene or p-xylene)) at T = 298.15 K and atmospheric pressure. The mixed isomers (xylenes) are also used as a mixed-solvent like the individual isomers and phase behaviour of (water + acetic acid + xylenes) is investigated. The experimental LLE data were correlated using the NRTL model, and the binary interaction parameters were obtained. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer-Tobias correlation. (c) 2013 Elsevier Ltd. All rights reserved.