This paper investigates the stability of molybdenum base silicides, which are located in combustion chambers and in an endothermic environment, for use in radiant tubes for heat treatment. The subject matter was plasma-sprayed molybdenum disilicide, pentamolybdenum trisilicide, hot-pressed molybdenum disilicide, and molybdenum disilicide composites containing SiC and silicon nitride reinforcements. Results of the investigation show that the oxidation resistance of plasma sprayed molybdenum disilicide can be detrimentally effected due to the silicon loss that occurs during the high temperature plasma spray process. Paper includes a German-language abstract.