The invention relates to an electronically controlled metering system having at least one sensor for injection of a reducing agent, especially a urea solution, into the exhaust gas stream of an internal combustion engine for selective catalytic reduction, the metering system being connected/connectable to a tank from which the reducing agent can be taken, the reducing agent being conveyed by means of a pump, the metering system having a first line which carries the reducing agent and the metering system having a compressed air supply and a second line which carries compressed air and at least one nozzle which is coupled to both lines and by which the reducing agent together with the compressed air can be injected into the exhaust gas stream, the metering system in the line which carries the reducing agent having at least one damping element for equalization of pressure fluctuations.