A process for the production of a mixed oxide powder, that contains as chief constituent TiO.sub.2 in the form of anatase and as minor constituents at least one of the catalytically active oxides MoO.sub.3, WO.sub.3 and V.sub.2 O.sub.5, suitable for use as a catalyst for the removal of nitrogen oxides, comprising (a) partially neutralizing a titanium dioxide hydrate suspension containing sulphuric acid with an alkaline liquor to a pH value between about 4.0 and 6.0 at temperatures between about 20.degree. and 100.degree. C., (b) filtering the suspension from (a) to produce a filter cake and intensively washing the filter cake, (c) adding to the filter cake from (b) at least one water-soluble salt of at least one of the metals Mo, W and V in solid or dissolved form, and (d) drying the filter cake from (c) and calcining it at a temperature between about 300.degree. and 750.degree. C.