Liquid-liquid equilibria (LLE) data for the ternary systems of water + acetic acid + 1,2,4-trimethylbenzene and water + acetic acid + 1,3,5-trimethylbenzene were measured under atmospheric pressure at (303.2-343.3) K. The reliability of the experimentally determined tie-line data was verified by comparison with the literature data. Both the nonrandom two-liquid (NRTL) and the universal quasi-chemical activity coefficient (UNIQUAC) models were adopted to correlate the experimental LLE data, and the binary model interaction parameters were obtained. The RMSD values as low as 0.89% and 0.51% were obtained for the two models, respectively, which shows that the experimental LLE data have been successfully correlated by both the NRTL and the UNIQUAC models. The relevant model parameters could be useful for the simulation and optimization of the related separation process. Moreover, the distribution coefficient and separation factor of acetic acid in the two ternary systems were calculated and discussed in detail. (C) 2016 Elsevier B.V. All rights reserved.