Alkylations of alpha-methylnaphthalene with long-chain alkenes (mixed C11-12 olefins) in the presence of room temperature ionic liquids and zeolite catalysts have been investigated. The influences of various parameters, such as type and dosage of catalyst, molar ratio of alpha-methylnaphthalene to alkenes, reaction temperature, and reaction time were studied. The EtxNH4-xCl-AlCl3 (x = 1-3, 0.67-0.75 molar fraction of aluminum trichloride) ionic liquids, compared with HY, USY zeolite and the other ethylamine-containing ionic liquids, were found to catalyze the reaction with high conversion of long-chain olefins and good selectivity for monoalkylated methyl naphthalene. (C) 2004 Elsevier B.V. All rights reserved.