A soil material containing 81% Fe2O3 that is inactive towards H2O2 was used to prepare composites with charcoal obtained from sucrose. Composites obtained by heating under air at 400, 600, 700 and 800 degrees C were characterized by total Fe, Fe2+ and Fe3+ chemical analyses, Mossbauer spectroscopy, visible diffuse reflectance, X-ray diffraction and surface area determination. The catalytic activities of the composites were monitored by methylene blue degradation. The results indicate that the activity towards methylene blue degradation was strongly enhanced after heating at 600 degrees C, with almost 100% color removal. Fe2+ in the magnetite structure was mainly responsible for the catalytic activity the composites and the mechanism of methylene blue degradation beginning via (OH)-O-center dot radicals produced by Fe2+ in the magnetite structure and H2O2. The proposed mechanism is supported by ESI-MS analysis. (C) 2010 Elsevier B.V. All rights reserved.