(Liquid + liquid) equilibrium (LLE) of the ternary (water + acetic acid + toluene) system was investigated at temperatures of (288.2, 298.2, and 313.2) K, under atmospheric pressure. This chemical system is frequently used in liquid-liquid extraction investigations. The results show that the distribution coefficient of acetic acid between organic and aqueous phases rises with increasing temperature, but the separation factor decreases within the temperature range covered. Meanwhile, a maximum extraction factor (about 100) was achieved for the solute aqueous phase mass fraction around 0.27 at T = 288.2 K. The tie line data for this system were sufficiently correlated by Othmer-Tobias and Hand equations. The experimental results were used to obtain binary interaction parameters as predicted by the non-random two liquid (NRTL) and universal quasi chemical (UNIQUAC) equation models using the Aspen Plus simulator. Root mean square deviation (RMSD) values as low as 0.0119 and 0.0139 were obtained for these models, respectively; indicating excellent correlation results for the provided experimental solubility data. (C) 2012 Elsevier Ltd. All rights reserved.