An apparatus for the controlled proportioning of gases to be delivered to a consumer comprises a mixed gas line containing the mixed gases to be delivered to the consumer which is connected to a plurality of separate gas supply lines. Each of the supply lines includes a quick-acting, electrically controlled valve which is controlled by control means which is effective to deliver a control pulse to open and close the valve in accordance with a set time slot pattern. For this purpose, the controller advantageously includes means for sensing the pressure in each of the supply lines and the mixed gas line and for regulating the quick-acting valves in accordance with one or more input signals which are fed to a computer section of a controller which has an actuator section which is operated in accordance with the sensed information and the input signals to carry out the supply of the gases in the set time slot pattern. The controller delivers one pulse per time slot pattern, the minimum length of the pulse being determined by the minimum switching time of the control valve and its maximum length being determined by the division of the time slot pattern. For gas amounts smaller than the corresponding minimum pulse times at each position of the time slot pattern, pulses are delivered only at certain points of the pattern.