Equilibrium tie line data have been determined for the two ternary liquid systems, namely {dodecane + propylbenzene + [mebupy][BF4]} and {dodecane + butylbenzene + [mebupy][BF4]} at temperatures (313, 323, and 333) K and atmospheric pressure. The effects of temperature and solvent to feed ratio upon solubility, selectivity, and distribution coefficient were investigated experimentally. The reliability of the experimental data was tested using the Othmer-Tobias correlation. The experimental results were regressed to estimate the interaction parameters between each of the three pairs of components for the UNIQUAC and the NRTL models as a function of temperature. In addition, the LLE data were also correlated with the UNIQUAC and NRTL models in a satisfactory manner. (C) 2011 Elsevier Ltd. All rights reserved.