Liquid-liquid equilibrium for cyclohexane + ethylbenzene + sulfolane have been measured at the temperatures (303.15, 313.15, and 323.15) K and at atmospheric pressure. The reliability of the experimental data was tested using the Othmer-Tobias correlation. The liquid-liquid equilibrium (LLE) data were then analyzed using a UNIFAC model with group interaction parameters extracted from the LLE data bank (UNIF-LL) and a NRTL version with temperature-dependent binary parameters determined from the experimental LLE data (NRTL/2); both as programmed by the Aspen Plus simulator. On the basis of the analysis of these data, both models represented the experimental data with sufficient accuracy as revealed from the very small values of the root-mean-square error (RMSE) and the average absolute deviation (AAD) in composition.