The thermal fogging device using a liquid, comprises: an assembly (3) for producing a pressurised hot gas flow an 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.
