Liquid-liquid equilibrium (LLE) data for {1-ethyl-3-methylimidazolium diethylphosphate ([emim][DEtPO(4)]) or 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO(4)])} +/- 4,6-dimethyl-dibenzothiophene (4,6-DMDBT) + dodecane systems, at (298.2 and 313.2) K and atmospheric pressure (approximate to 95 kPa), were determined by refractometry. 4,6-DMDBT is one of the most difficult diesel sulfur pollutants to remove by the conventional process of hydrodesulfurization (HDS). Extraction of 4,6-DMDBT from dodecane (used as model diesel oil) was analyzed in terms of solute distribution coefficient, solvent selectivity, and percent of extraction. The results indicate that [emim][DEtPO(4)] is a better solvent for extractive desulfurization of dodecane than [emim][EtSO(4)]. The Hand and Othmer-Tobias correlations, used to ascertain the quality of the experimental data, presented R(2)> 0.98 for systems with [emim][DEtPO(4)] and R(2 >) 0.96 for systems with [emim][EtSO(4)]. The nonrandom two-liquid (NRTL) model was used to correlate the LLE data and showed root-mean-square deviations between experimental and calculated mole fractions 0.0002.