Abstract: The invention discloses a humidifying device which consists in a thermally conductive casing which is adapted and correctly dimensioned to fit over a conventional electrical radiator without preventing it from heating the ambiant air simultaneously. The casing is destined to be at least partially filled with water, and upon the radiator generating heat, the water temperature will gradually increase and water will evaporate into the ambiant air through outlets in the top of the casing due to the heat being conducted through the radiator and casing to the water. The water vapor outflow rate can be selectively adjusted by means of a pivotable heat deflector or alternately by adjusting the distance between the radiator and the casing. A sponge member filled with bactericide is inserted into the casing and is submerged in water.