Regioselective mononitration of simple aromatic compounds has been investigated in several different air- and moisture-stable ionic liquids. Use of a mixture of nitric acid and acetic anhydride as the nitrating reagent gave rise to enhanced reactivitites and improved para-selectivities for halogenobenzenes compared to those in a molecular solvent, CCl4. In addition, the ionic liquid could be recovered easily and reused, which opens up the possibility of a more economic process.