The design and operation of the process to extract aromatics from petroleum intermediates via solvent extraction can be enhanced in terms of efficiency by access to liquid liquid equilibrium (LLE) data. This study serves to contribute LLE data for a heavy alkane, aromatic, and solvent mixture, which is of limited availability in the open literature. Ternary LLE phase compositions were experimentally measured and thermodynamically modeled for the systems N-formylmorpholine (NFM) + toluene + (n-nonane or n-decane) at 303.2, 323.2, and 343.2 K and 101.3 kPa. The direct analytical method was used to obtain the LLE data using a double-walled glass cell. The phase equilibrium samples were quantitatively analyzed using gas chromatography. The ternary systems were successfully correlated using the non-random two -liquid and universal quasichemical thermodynamic models. The effectiveness of using NFM as an alternative solvent to extract toluene from a mixture containing n-nonane or n-decane was evaluated by determining the selectivity. The plait point for the systems measured was determined using the graphical Coolidge method. All systems studied were found to exhibit type I ternary LLE behavior, and relative selectivity was greater than unity, indicating that the extraction of toluene from heavy alkanes is feasible using NFM.