Mesoporous manganese oxide (MPMO) from reduction of KMnO4 with maleic acid, was obtained and characterized in detail. The characterization of the material was confirmed by high-resolution transmission electron microscopy (HRTEM), X-ray powder diffractometry (XRD) and N-2 sorptometry. The results showed that MPMO is a pseudo-crystalline material with complex network pore structure, of which BET specific surface area is 297 m(2)/g and pore size distribution is approximately in the range of 0.7-6.0 nm. The MPMO material turns to cryptomelane when the calcinating temperature rises to 400 degreesC. The optimum sol-gel reaction conditions are KMnO4/C4H4O4 molar ratio = 3, pH = 7 and gelation time > 6 h. (C) 2003 Elsevier Ltd. All rights reserved.