Abstract: The present invention relates to an apparatus for catalytic cleaning, particularly de-nitrification, of waste gases, said apparatus comprising a heat exchanger (12) for exchanging heat between the already cleaned gas and the raw gas to be cleaned, a heating channel (14), in which additional heat is supplied to the raw gas and which joins the heat exchanger (12), a jetting unit is provided in the heating channel (14) for supplying ammonia and an arrangement of catalysts (16) containing catalysts, which is attached to the heating channel (14) and is placed above the heat exchanger (12), wherein the arrangement of catalysts (16) and the heating channel (14) are connected with each other via an essentially U-shaped deflection hood (24) and the heat exchanger is one of type working in counter flow.