SiO2/Fe2O3 mesoporous composites have been prepared with a nanoscale casting process using an activated carbon (AC) template in supercritical carbon dioxide (SC CO2). The composite precursor and acetone solvent (for Fe2O3 precursor) were dissolved in SC CO2, and then coated on the AC in the desired supercritical condition. After removal of the AC template by calcinations in air at 600 degrees C, SiO2/Fe2O3 mesoporous composite were obtained. Temperature, pressure, and composite precursor ratio effects were studied. Scanning electron microscopy result shows that the porous structure of AC template had been well replicated by the composite product. Transmission electron micrograph indicates that nano iron oxides were well dispersed in the composite product.