A device for reducing the emission of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) from transition metal-containing catalyzers for selective catalytic reduction of nitric oxides in the exhaust gas of an internal combustion engine by means of ammonia and/or reducing agents which split off ammonia. At least one catalyzer for oxidizing hydrocarbon-containing PCDD precursor substances and PCDF is arranged upstream of the at least one transition metal-containing SCR catalyzer and/or at least one catalyzer for degrading precursor substances for degrading the polychlorinated dibenzodioxins and/or polychlorinated dibenzofurans is arranged downstream of the at least one transition metal-containing catalyzer. The at least one catalyzer for degrading PCDD and PCDF and/or the at least one catalyzer for oxidizing hydrocarbon-containing precursor substances thereof are/is additionally active for the reduction of nitric oxides by means of ammonia.