Abstract: The mass-transfer apparatus is based on the principle of the gas washer in which a liquid is injected into the hot gas stream. The apparatus consists essentially of a gas feed pipe (1), which discharges vertically into an injection chamber (2) of greater diameter. Connected to the injection chamber (2) is a mass-transfer duct (12) with a diffuser (13). The injection chamber (2) is closed at its upper end against the gas feed pipe (1) with an annular roof (4). In the annular roof (4) are arranged liquid nozzles (5), directed at an angle downwards. The gas feed pipe (1) does not terminate flush with the annular roof (4) but is extended into the injection chamber (2) in the form of a gas skirt tube (8), so that the liquid nozzles (5) in the annular roof (4) are protected from the hot gas stream.