Described is a device (1) for nebulising substances for aerosols comprising an outfeed duct (11) for the nebulised substance positioned in fluid communication between a nebulising chamber (C) and an outfeed section (11 b) of the outfeed duct (11) which can be used by a patient for inhaling operations, a separating element (12) configured to divide the nebulising chamber (C) in at least two separate sectors (C1, C2), and movement means (17) to move the separating element (12) in such a way as position at least partly at least one of the two sectors (C1, C2) facing at an infeed opening (11 a) of the outfeed duct (11) to adjust the flow rate of the fluid coming from the outfeed duct (11) of the device (1).
