Nano-sized Ta2O5/HfO2/carbon clusters composite material has been successfully obtained by the microwave-irradiated calcination of a (EtO)(4)Ta(acac)/HfCl4/epoxy resin complex. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD), scanning electron microscopy (SEMI) and transmission electron microscopy (TEM). The ultraviolet-visible (UV-vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. XPS spectral examinations suggest the possibility of a two-step electron transfer in the process of Ta2O5 -> carbon clusters -> HfO2 with an oxidation site at Ta2O5 particles and a reduction site at HfO2 particles. The reduction reaction of methylene blue with the calcined materials under the visible light irradiation has also been examined. (C) 2008 Elsevier B.V. All rights reserved