The milling by-product of rice, rice husk, constitutes a major waste of the agricultural industry. It is mainly used as a fuel additive for various purposes, leaving behind residual ash which is rich in silica (Biogenic silica). In the present project, rice husk silica was impregnated with Fe3+, Sb3+, Bi3+ and Al3+ from both their aqueous and organic solutions. The resultant catalysts were activated at 120degreesC and 550degreesC and used for the Friedel-Crafts benzylation of benzene using benzyl chloride. (C) 2003 Society of Chemical Industry.