A dispensing device for a volatile substance includes a diffuser (10) including a diffuser body a storing reservoir (5) in fluid communication with the diffuser (10) and configured to store a liquid (6) containing at least one volatile substance an osmotic pump (1) including an osmotically active substance (3) in contact with a first surface of a semipermeable membrane (2) of the osmotic pump (1), wherein the osmotically active substance is capable of forming a driving fluid (4) to act on the liquid (6) in the storing reservoir (5) and to drive the liquid (6) to the diffuser (10), when a second surface of the semipermeable membrane (2) is brought in contact with a solvent.
