Toluene was alkylated with benzyl chloride and benzyl alcohol using a series of clays (KSF, KSF/0, K0, KP10, K10, KS from Sud Chemie) obtained by treating a bavarian bentonite by different acids and a Hungarian bentonite (Mad) as catalysts in a batch reactor. The catalysts were characterized by chemical analysis, thermal analysis, nitrogen adsorption, solid state nuclear magnetic resonance, X-ray diffraction. The acidity of these solids was determined by infrared spectroscopy using pyridine as molecular probe. The structure, specific surface area, and distribution of Lewis/Bronsted acidity of these clays can be changed to a great extent by acidic or thermal treatment. The rate of alkylation is related to Bronsted acidity when the substrate is benzyl alcohol. When benzyl chloride is used as alkylating agent, the Fe3+ content of the clay controls the activity, and iron containing clays show high activities in spite of their low Lewis acidities.