A newer type of metal salt-metal ion exchanged Montmorillonite (Mont), MCl2-Mn+-Mont (M = Ni, Cu, Zn; n = 2) have been prepared and evaluated as solid acid catalysts for Friedel-Crafts reactions particularly for benzylation of benzene. The activity of such composites depends upon the amount of loading of metal salts on the metal ion exchanged-Mont support and 1.5 mmol loading per mole of the support shows the highest activity. Activation temperature of the composites also plays an important role and 150 +/- 10degreesC is the optimum region. ZnCl2-Zn2+-Mont (1.5 mmol, 0.926 g) and Zn2+-Mont (1.5 mmol, 3.33 g) composites show about 97% conversion during 24 h of reaction time and therefore, the former composite shows an advantage over the latter in respect of total amount of catalyst weight to be used. The composites show both Bronsted and Lewis acidities which were determined by thermal desorption and differential scanning calorimetric (DSC) techniques. The composites were also characterized by thermal analysis and X-ray diffraction (XRD) measurements. (C) 2003 Elsevier Science B.V. All rights reserved.