Abstract: A preparation process of aromatic ketones by a Friedel-Crafts acylation reaction in an ionic liquid of formula (I), in the absence of any other catalyst and/or solvent. In formula (I), [Q]+ is selected from substituted-imidazolium cations, substituted-pyridinium cations, ammonium cations, and phosponium cations. It allows to carry out Friedel-Crafts acylations with good yields and high selectivity in para position of the Friedel-Crafts aromatic substrate without using chlorine-containing solvents and conventional Friedel-Crafts catalysts. It is industrially useful because provides a “Green Chemistry” technology for carrying out Friedel-Crafts acylations of general aplicability.