Ionic liquids can extract mono- and poly-aromatic sulfur and nitrogen compounds from gasoline and diesel and they perform better than conventional solvents. The extraction capacity of several ionic liquids for these heterocyclic compounds is determined and compared to the extraction capacity for aromatic hydrocarbons. Furthermore, the experimental results obtained are evaluated in view of the results reported in literature. It is shown that the ionic liquids investigated in this work are able to extract sulfur as well as nitrogen-containing aromatics in preference to aromatic hydrocarbons. Moreover, the ionic liquids [3-mebupy]N(CN)₂, [4-mebupy]N(CN)₂ and [bmim]C(CN)₃ are superior to sulfolane, which has been used as a benchmark and also outperform the ionic liquids reported in literature so far. Finally, it has been shown that nitrogen-containing hetero-aromatics are significantly better extracted than sulfur-containing hetero-aromatics.