The invention relates to a mixer for a device for selective catalytic reduction of exhaust gases from internal combustion engines. The mixer comprises a structure of mixer elements through which the mixture of exhaust gas and reducing agent is to flow. The mixer elements have an electric current flowing through them for electrical heating due to the electrical resistance thereof. The invention further relates to a device for selective catalytic reaction of exhaust gases from an internal combustion engine having an exhaust gas pipe leading to a mixer according to the invention and having a reducing agent pipe which is connected to a reservoir for reducing agent and which opens into the exhaust gas pipe in the flow direction upstream of the mixer, and a catalyst in the flow direction downstream of the mixer.