Abstract: To produce a gas mixture by the saturation method, liquid is fed from a stock vessel to a separate reaction vessel. A carrier gas enters through a dip tube into the liquid present in the reaction vessel and is saturated by the liquid. The reaction vessel consists, for example, of quartz and is disposed in a metal block connected to a temperature control system. A level sensor fitted to the reaction vessel controls a flow regulation instrument on the liquid feed. The volume of the reaction vessel is substantially smaller than the volume of the stock vessel. Only the temperature of the reaction vessel is controlled. Temperature control of the stock vessel is not required. The saturation process in the reaction vessel takes place uniformly, independently of the temperature and the level in the stock vessel.