Abstract: A projection television display tube having an evacuated envelope (1) with a display window (4) which has a display screen (5) on its inside and in front of which a light-permeable second window (6) is provided on the outside, a cooling liquid flowing through the space (7) between the display window (4) and the second window (6) from at least one inlet aperture to at least one outlet aperture. When in such a projection television display tube a cooling jacket(8) is provided at the area of the windows (4, 6) and around the said space (7) and is provided with at least one duct (9) and one pump (16) with connecting nipples (17,18) which transport the cooling liquid from the outlet aperture to the inlet aperture or apertures of the said space (7), an effective cooling is obtained with a power up to 40 W without outer pipes and without heat exchangers. By the forced circulation of the cooling liquid a good temperature compensation is obtained so that fewer stresses occur in the glass of the display window.