Liquid-liquid equilibrium (LLE) data of ternary system (n-heptane + toluene + aniline) at 20 degrees C is experimentally investigated in the present work. The reliability of this data was ascertained from Othmer-Tobias plots. For the simulation procedure, we have utilized the NRTL and UNIQUAC activity coefficient models for the prediction of the liquid-liquid equilibrium of this system, the new interaction energy parameters for these models were determined. Recently, several optimization methods such as Nelder-Mead algorithm (NMA) and genetic algorithm (GA) have evolved as alternative and reliable strategies for solving global optimization problems including parameter estimation in thermodynamic models. However, these methods have been applied and compared with respect to other tools strategies such as ASPEN PLUS, HYSYS and CHEMCAD simulators in the context of parameter estimation for LLE data modeling. In conclusion, the obtained results of the prediction of liquid-liquid equilibrium are compared with the experimental values. These results were obtained to justify that the process of optimization recommended is very practical to estimate the interaction parameters of this ternary system. (C) 2011 Elsevier B.V. All rights reserved.