AlCl3-based ionic liquids (ILs) supported on silica and MCM-41 have been used for disproportionation and dealkylation of dodecylbenzene (DDB) at low reaction temperature. AlCl3-based ionic liquids supported on MCM-41 were highly active for the conversion of DDB. Up to 55 mol% conversion and selectivity to benzene at 120 degrees C after 2 h reaction time were found for DDB transformation. Yield ratios between didodecylbenzenes and benzene are lower than 1 over such AlCl3-based ionic liquids supported on MCM-41. That means a part of the 1-dodecylbenzene is catalytically dealkylated and not disproportionated. An induction period has been found for such a catalyst. The catalytic dealkylation of DDB requires a high density of very strong Lewis acid sites. A detrimental influence of n-decane (used as solvent) on DDB conversion was observed. The presence of an increased amount of naphthalene in the initial reaction mixture led to a strong decrease of selectivity towards didodecylbenzenes in favor of selectivity for benzene and formation of dodecylnaphthalene. (C) 2009 Elsevier B.V. All rights reserved.