A method for adding at least one, in particular liquid, reactant, to an exhaust gas stream of an internal combustion engine includes adding a reactant flow to the stream downstream of an element provided for an at least partial conversion and/or at least partial elimination of at least one component of the stream, so that at least part of the reactant flow impinges on the element. This achieves rapid evaporation of the reactant flow. Impinging on the element, which is hot during operation, i.e. at temperatures of 400° C. and more, causes rapid evaporation and, because of a preferably porous coating of the element, take-up of the reactant solution into the element with successive evaporation. Urea, in particular, can be evaporated quickly, effectively and virtually completely upon introduction into an exhaust system as a reducing agent for selective catalytic reduction of nitrogen oxides, in particular in a downstream SCR catalytic converter.