A DC gas discharge lamp includes an anode and a cathode having a first cathode segment, which forms the surface of the cathode at least in a region of the cathode which faces the anode and has an arc attachment region, within which an arc burning between the cathode and the anode attaches during lamp operation as intended. The first cathode segment consists of tungsten with at least one emitter material for reducing the work function of electrons from the cathode. The cathode is embodied in a manner free of thorium. The at least one emitter material has a melting point of less than 3200 K. At least one part of the surface of the cathode outside the arc attachment region is formed by a diffusion barrier for the at least one emitter material.