A process for de-icing an air intake cowling (5) of a reaction motor, having an air intake lip (6a), a de-icing system (10) and acoustic attenuation part (11), where the acoustic attenuation part includes separate islands (11a) formed by a sandwich of an acoustically resistive porous layer forming a portion of the external envelope (6i) of the fan channel delimited by the air intake lip, a cellular core, and a reflector (13), has the steps of sending into the lip, preferably in the direction of the acoustic attenuation islands, the warm fluid under pressure of the de-icing system, and causing the fluid to escape outside the cowling, through one or several openings (20) of suitable shape and size, provided in the cowling.