Iron-containing mesoporous mesophase materials Fe-MMM-2 have been synthesized by a sol-mesophase route under mild acidic conditions and characterized by DRS-UV-vis, XRD, and N-2 adsorption measurements. It was found that pH of the synthesis solution and iron content in the samples affect both the textural characteristics and the state of iron atoms. Isolated iron species predominate in silica framework under Fe < 2 wt% and pH similar to 1.0 or Fe similar to 1 wt% and pH < 2.0. These species are stable to leaching and highly active in full H2O2-based phenol oxidation. The increase in iron loading and pH of the synthesis solution lead to the agglomeration and formation of oligomeric iron species, which, in turn, results in the reduction of the catalytic activity of Fe-MMM-2 and the increase of iron leaching. (c) 2007 Elsevier B.V. All rights reserved.