An ultra-high pressure discharge lamp in which the disadvantage of the reduction of the illuminance maintenance factor due to formation of blackening and milky opacification in the discharge vessel and the disadvantage of formation of cracks in the discharge vessel is eliminated by the discharge vessel being made of a silica glass that contains 0.1 ppm by weight to 290 ppm by weight hydrogen. Further advantages are obtained by the silica glass having a content of OH radicals that is at most 1 ppm by weight and a content of aluminum in a range of 2 ppm by weight to 30 ppm by weight.