A device and a process for controlling a respirator with inclusion of an oxygen saturation value (34) for compensating a device-dependent time response (15), a physiological time response (16) and a measuring method-dependent time response (17) are described. The device-dependent time response (15), the physiological time response (16) and the measuring method-dependent time response (17) are determined in a continuous sequence and a run time of a change in the oxygen concentration from the metering means (9) in the respirator to the patient (4) is determined and taken into account in regulating the oxygen concentration.