The tie-line end compositions of six ternary systems of methanol(1) +hexadecane(2) +nitrogen-containing compounds(3) were experimentally determined at 298.15 K. This work was carried out to find solvent extraction possibility of heterocyclic nitrogen-containing compounds from the middle distillates. The heterocyclic nitrogen-containing compounds act as an inhibitor in the ultra-low sulfur diesel manufacturing process in the oil industry. Measured tie lines have been correlated using the NRTL equation and it showed good agreement. Besides, the extracting capabilities of methanol to heterocyclic nitrogen-containing compounds were investigated with respect to distribution coefficients and selectivities.