The synthesis and use for soot combustion of praseodymium oxide with three-dimensionally ordered macroporous (3DOM) structure is described. This novel PrOx-3DOM catalyst is presented as an improved noble-metal-free alternative to CeO2 as soot combustion catalyst. The PrOx-3DOM catalyst presents a defined 3DOM structure with high macropores volume, which significantly enhances the solid-solid soot-catalyst contact. This enhanced contact, together with the improved reducibility of PrOx regarding CeO2, ameliorate the active oxygen production and its transfer to soot particles, improving the soot combustion with O-2. In addition, the higher ability of PrOx to oxidize NO to NO2, improves the soot combustion in a higher extent than CeO2 in presence of NOx. The catalytic activity of PrOx-3DOM after several soot combustion cycles is also confirmed.