- The essentially complete mineralization (>95% total organic carbon elimination) of 2,4,6-trichlorophenol by a CWO is reported at a very mild operating conditions (120 °C, P O 2 = 10 bar ), with the use of a nanocasted Mn–Ce-oxide catalyst. This unique catalyst was prepared by fabrication of a thin nanometric layer of Mn–Ce oxides inside the tubular mesopores of SBA-15 silica using internal gelation of corresponding metal chlorides. Crystallization of this oxide layer at 700 °C, followed by removal of silica matrix, yielded a nanostructured mixed-oxide catalyst with surface area up to 316 m 2 /g. It demonstrated superior textural, structural, and surface oxygen properties compared with a reference co-precipitated bulk Mn–Ce-oxide catalyst. This is a result of reduction and equalization of the crystal size of both oxide-phases Mn 2 O 3 and CeO 2 at the level of 2–3 nm, providing the full availability of their surface for reacting molecules. The performance measured with the novel catalyst indicates a major improvement in the efficient application of CWO processes for complete purification of complex waste streams.