A low-pressure gas discharge lamp is described, which is equipped with a gas-discharge vessel containing an inert gas filling as the buffer gas and an indium, thallium and/or copper halide, and with electrodes and with means for generating and maintaining a low-pressure gas discharge, wherein it has, as the electron emitter substance, a mixture of BaO, SrO, CaO and MgO, wherein: a) the molar proportion of BaO is less than 1 percent by weight b) the molar proportion of SrO is less than 10 percent by weight c) the sum of the molar proportions of CaO and MgO is greater than 90 percent by weight, wherein the CaO proportion in the CaO/MgO mixture lies between 10 and 90 percent by weight.