A combined component consists of a heat exchanger and a reactor. The heat exchanger is designed in a plate form, and flow spaces for a first medium and a second medium are alternately defined between successive plates. The plates of the heat exchanger are configured as essentially annular. The heat exchanger has, substantially perpendicularly to the plates, a tubular outer wall and a tubular inner wall. The reactor is surrounded by the inner wall of the heat exchanger. The product of the reactor is conducted through supply orifices on the inner wall of the heat exchanger into the flow spaces for one of the two fluids in the heat exchanger.