The disclosure relates to a nozzle for a device for the dermo-cosmetic treatment of dark skin spots by cyto-selective cryotherapy comprising a spray jet supplied by a tank of pressurised liquified cryogenic gas. The nozzle comprises an upper ring for connecting to a shell, extended by a central body of which the side wall which narrows downwards has longitudinal openings and delimits a gas expansion chamber communicating with a frustoconical dispersal conduit arranged inside an end piece to be applied to the skin and opening to the outside through a discharge port.