Alkylations of 1-and 2-methylnaphthalene with long-chain alkenes in different alkyl-containing amine ionic liquids were investigated at room temperature. The effects of both anions and cations of ionic liquids on the alkylations were studied in detail. Results show that the anions determine, to a large extent, the physical and chemical properties of ionic liquids, but organic cations mainly influence physical properties, and have only a little impact on the catalytic performance. High conversion of alkylating agent and excellent selectivity for the desired products were obtained. The products and unreacted reactants were easily isolated from catalysis systems by extraction with cyclohexane. Thanks to the less expensive reagents and the easier synthesis process, methyl and ethylamine chloroaluminate ionic liquids could become novel practical catalysts for long-chain alkylation of methylnaphthalene with alkenes. (c) 2005 Elsevier B.V. All rights reserved.