The solid-liquid equilibrium (SLE) phase boundaries of the ternary mixture of m-cresol, 2,6-xylenol, and tert-butyl alcohol and those of the three constituent binary mixtures were experimentally determined by means of the solid-disappearance method. Each of the m-cresol + 2,6-xylenol and tert-butyl alcohol + 2,6-xylenol mixtures exhibits one eutectic point, whereas the nt-cresol + tert-butyl alcohol mixture exhibits one congruent point and two eutectic points. The approach proposed by Ott and Goates (J. Chem. Thermodyn. 1983, 15, 267) was used to represent the melting point temperatures as functions of the mole fraction of one of the components. The formulation developed by Stoicos and Eckert (Chem. Eng. Sci. 1987, 42, 1137) for SLE calculations was used with the NRTL activity coefficient model of Renon and Prausnitz (AIChE J. 1968, 14, 135) to correlate the experimental data for the binary systems. On the basis of the information presented in the phase diagram, which shows all the eutectic and congruent points and the liquidus isotherms for the ternary system, two conceptual possible processes involving the use of tert-butyl alcohol as the adductive agent for separating a mixture of m-cresol and 2,6-xylenol are proposed.