The photocatalytic degradation of organic compounds in airstreams or in solution was studied by using the commercial HZSM-5 as photocatalyst. It was found that the commercial HZSM-5 had an unanticipated photocatalytic activity for ethylene, bromomethane and methyl orange. XRF and AAS analysis revealed that all of the HZSM-5 samples employed contain a trace amount of iron species. The photocatalytic activity of samples was proportional to the content of iron. The primary results of characterization by XRD, DRS, XPS and SPVS suggested that the most of Fe existed in framework of zeolite and in a tetrahedral coordination. The iron species might be excited by UV irradiation to form a charge transfer excited complex along with the ligands and an electron excited state of Fe3+, which are responsible for the photocatalytic behavior of zeolites. (C) 2004 Elsevier B.V. All rights reserved.