Abstract: In an installation for the electrostatic projection of powders for coating objects, a method of improving the efficiency of projection and deposit of the said powders consists of increasing the relative humidity of the projection gas in the immediate vicinity of the projection nozzle by means of mixing the jet of gas which conveys the coating powder, at the level of the projection nozzle, with a jet of auxiliary gas previously heated and humidified by means of an appropriate liquid. In an alternative method, there is comprised the further step of reducing the temperature of the main jet of gas before this main jet is mixed with the auxiliary gas.The apparatus for carrying the method into effect comprises the heating and humidifying devices for the auxiliary gas and a device for cooling the main gas.