A process serves for recoating a deactivated catalyst coating of a catalyst for converting harmful constituents from the exhaust gas of an internal combustion engine, particularly in a motor vehicle. In this process, washcoat and/or noble metal compounds are sprayed by means of an aerosol into the catalyst. The noble metal compounds are subsequently brought into their elemental state by means of a reducing medium flowing through the catalyst, after which the washcoat applied is dried by heat treatment or calcination. In an apparatus for carrying out the process, a first line for a carrier gas and a second line for the washcoat and/or the noble metal compounds are provided. The first line is arranged at least partly in a region before the catalyst within the second line and at its ends nearest the catalyst is provided with an atomization device. The second line opens into the catalyst,with there being provided after the catalyst a third line which opens into a separator from which the first and the second lines lead away.