A gas discharge lamp (1) equipped with a gas discharge vessel (2) enclosing a gas filling, said gas filling comprising a chalcogen selected from the group of sulfur, selenium or tellurium or a compound thereof, and with means for igniting and maintaining a gas discharge, comprising an electrode assembly (6-9) disposed in the discharge vessel, the electron-emissive material (9) of the electrode assembly comprising iridium or an alloy of iridium, providing a long-lived, efficient, compact, and high intensity white light source for applications such as general and professional illumination.