Two series of α-MnO2 materials were prepared via a similar method with surfactant cetyltrimethylammonium bromide (CTAB) and sodium dodecyl benzene sulfate (SDBS). The surfactants work both as shape directing agent and reduction initiator. The α-MnO2 synthesized with 0.2 M of CTAB showed a mesoporous structure with high surface area of 387.7 m2/g. It is very active in catalytic ozonation of 4-nitrophenol (4-NP) and total organic carbon removal, with higher catalytic stability than commercial MnO2. Using tert-butanol and p-benzoquinone as scavengers of different oxidative species, we found that superoxide radicals, rather than hydroxyl radicals, were mainly responsible for the degradation of 4-NP.