Liquid-liquid equilibria (LLE) of the multicomponent system water + methyl tert-butyl ether (MTBE) + synthetic reformate were studied under atmospheric pressure and at temperatures 288.15, 298.15, 308.15, and 318.15 K. The synthetic reformate was composed of o-xylene, 2,2,4-trimethylpentane, and cyclohexane. The mutual reformate-water solubility with addition of MTBE was investigated. The system we studied formed a type 2 liquid-liquid phase diagram. The results were used to estimate the interaction parameters between each pair of components in the system for the NRTL and the UNIQUAC models. The UNIQUAC and NRTL models fit the experimental data with an average root mean square deviation (rmsd) of 0.2290 and 0.2189%, respectively.