Abstract: The invention provides a device which supplies the time resolved secondary air according to the exhaust valve timing of each cylinder at desired time and in desired amount while the engine is cold so as to enhance the mixing and achieves sufficient oxidation of exhaust gases, as a result, to reduce emissions. The device includes, an air compressor for producing the secondary air; a distributor for distributing the secondary air to an exhaust system for a cylinder in the exhaust stroke, connected to the exhaust system by a distributing means; and a timing means for operating the distributor while an exhaust valve of the cylinder is open according to the exhaust valve timing of the cylinder following the sequence of engine combustion.