Liquid-liquid equilibrium (LLE) data of water+acetic acid+dimethyl succinate were measured at 298.2, 308.2, and 318.2 K. Complete phase diagrams were obtained by determining binodal curves and tie lines. The reliability of the experimental tie line data was confirmed by using the Othmer-Tobias correlation. The UNIFAC and modified UNIFAC model were used to predict the phase equilibrium data in the ternary system. Distribution coefficients and separation factors were evaluated for the immiscibility region. (c) 2005 Elsevier B.V. All rights reserved.