1-Butyl-3-methylimidazolium tetrachloroaluminate ionic liquid (IL) was synthesized and tested for its capability to extract organic sulfur species from real, refinery obtained hydrocarbon fuels. The fuels consisted of sulfur-rich gasoline and diesel as well as pretreated, partially desulfurized gasoline and diesel. The IL-extracted fuels were then analyzed for total sulfur, nitrogen, and chlorine. Total sulfur was significantly lowered in all tested fuels. Nitrogen levels were also significantly reduced mainly due to a pretreatment with molecular sieve. Only traces of chloride originating from the IL could be detected in three of the four samples after all extraction stages. Sulfur-speciation analyses revealed that some sulfur compounds in the feed were converted to new compounds.