In this work, the ability of some ionic liquids ([C(8)mim][BF(4)], [C(8)mim][NTf(2)], and [C(2)mim][EtSO(4)]), which have shown to be suitable as extraction solvents for the desulfurization of fuel oils, has been tested to carry out simultaneous denitrogenation. For this purpose, the liquid-liquid equilibria of these ionic liquids with pyridine and n-hexane have been determined at 298.15 K and atmospheric pressure. With the idea of giving useful parameters for the design of extraction units, the simultaneous correlation of five ternary systems involved in the gasoline and diesel desulfurization was carried out with the nonrandom two-liquid (NRTL) equation. The best results were achieved for a value of the nonrandomness parameter alpha = 0.3.