It is well known that room temperature ionic liquids (Ils) have the potential for serving as efficient reaction media in the Friedel-Crafts reactions of naphthalene. In this work, three ionic liquid systems prepared with AlCl3 were used as reaction media for the alkylation of naphthalene with different reagents. The following cations were used to prepare the chloroaluminate(III) ionic liquids: 1-butyl-3-methylimidazolium [Bmim]; 8-butyl-1,8-diazabicyclo[5,4,0]-undec-7-enium [bDBU] and 5-butyl-1,5-diazabicyclo[4,3,0]-non-5-enium [bDBN]. Ionic liquid systems are easy to prepare and show interesting catalytic properties. The thermal stability and structural NMR spectra of the ionic liquids were studied. The Ils rendered this reaction green characteristics. The conversions and reaction yields produced by the alkylation reaction of naphthalene with ethyl bromide and isopropyl chloride in the three ionic liquid systems were compared. (c) 2006 Elsevier B.V. All rights reserved.