AlMCM-41 materials with SUM ratios 25,50,75 and 100, synthesized following standard procedure were well characterized with XRD and surface area measurements. Acidity of the catalyst material was determined by stepwise temperature desorption (STPD) of ammonia. Liquid phase isopropylation of naphthalene with isopropanol in n-hexane medium under autogeneous pressure was performed in the temperature region 453 and 523 K. The main products of the reaction mono and dialkylated naphthalenes were analyzed and identified by gas chromatography and confirmed by GC-MS. The conversion and selectivity of the products are discussed from the point of view of catalyst characteristics and reaction conditions. The reaction was also carried out over HM, Hbeta, HY and HZSM-5 to have a comparative understanding of the different catalyst systems. (C) 2002 Elsevier Science B.V. All rights reserved.