Montmorillonite K10 was modified by treating it with FeCl3 dissolved in acetonitrile and water. The catalysts thus prepared were activated at different temperatures and were used for the reaction of benzyl chloride with various arenes. The reactions were carried out at different temperatures and it was found that the difference in the activity was marked when the reaction was carried out at 40 degrees C. The maximum activity was associated with Montmorillonite K10 modified by FeCl3 in acetonitrile solution and activated at 120 degrees C.