The thermal fogging device using a liquid, comprises:an assembly (3) for producing a pressurised hot gas flowan ejection pipe (5)a first liquid source (7)the means (9) for injecting into the ejection pipe (5) a metered liquid flow from the first liquid source (7),characterised in that the means (9) for injecting the metered liquid flow comprises a Venturi device (V) having an area (R), the cross-section of which is narrowed so as to enable the suction of the metered liquid flow.
