Abstract: A booth forming a spraying chamber for workpieces to be coated with powder particles has a substantially fully open front side, giving access to an electrostatic spray gun, and a substantially fully open rear side adjoining a housing of a detachable powder-collecting unit which is open toward the chamber while being separated therefrom by an apertured screen. Tubular filter elements in the housing of the powder-collecting unit, having air-permeable peripheral surfaces, communicate with the suction end of a blower in an overlying clean-air unit, thereby giving rise to an air stream which passes generally horizontally through the chamber from its front side to its rear side and entrains particles discharged by the spray gun. Particles bypassing the workpiece to be coated may traverse the apertured screen and cling to the surfaces of the filter elements from which they may be intermittently dislodged by an air blast directed into these elements from the clean-air unit.