Liquid-liquid equilibrium (LLE) data for ternary systems methylcyclohexane (1) + toluene (2) + N-formylmorpholine (NFM) (3) were determined under atmospheric pressure and at temperatures of (293.15, 303.15, 313.15, and 323.15) K. Complete phase diagrams were obtained by determining solubility and tie-line data. Tie-line compositions were correlated by the Othmer-Tobias and Bachman methods. The universal quasichemical activity coefficient (UNIQUAC) and the nonrandom two-liquid (NRTL) equation were used to correlate the phase equilibrium in the system using the interaction parameters determined from experimental data. Distribution coefficients, separation factors, and selectivity were evaluated for the immiscibility regions.