A simple and effective method for in situ synthesis of alpha-Fe nanoparticle/ordered mesoporous silica (OMS) composites is reported. Evaporation induced self-assembly (EISA) and carbothermal reduction (CR) are strategically combined by using amphiphilic triblock copolymer P123 as not only a template and but also a precursor of carbon material. P123 plays dual roles in assembly of mesostructure and reduction of ferric species. Thermogravimetric analysis-mass spectrometer was used to investigate the pyrolysis process of the wet gels. The synthesized composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS) and N(2) adsorption. The results showed that the composites possess ordered hexagonal mesoporous structure and the alpha-Fe nanoparticles with about 16 nm were well dispersed in mesoporous matrix. The carbon material resulting from P123 can reduce ferric species to alpha-Fe nanoparticles at 800 degrees C. Moreover, the formation mechanism for Fe nanoparticles in OMS matrix is proposed. (C) 2011 Elsevier B.V. All rights reserved.