A method and apparatus for separating particulate matter from a gas stream wherein dirty gas is moved first through a corona discharge zone, such as that provided by a plurality of rod-like electrodes each having a sharp-edged corona producing ribbon-like formation extending axially therealong, and then is moved through a plurality of mechanical filters of the cartridge type, each comprising a perforated, cylindrical, metal outer shell and an inner filter medium of foraminous dielectric material such as pleated paper. Each cartridge is closed at one end and open at the other from which cleaned gas flows out axially. The electrodes are located circumferentially of the filters with the filter and electrode longitudinal axes being substantially parallel. The conductive outer shells of the filter elements are connected to an electrical reference such as ground and the electrodes are connected to a relatively high electrical potential in a manner generating corona discharge between the electrode formations and the filter element shells. Collected particulate material in the filter media and on the shells is removed by introducing a controlled quantity of high pressure gas at predetermined times and at a location to induce a substantial flow of gas through the apparatus in a reverse direction.