Gas analysis on a metal bakable high vacuum system is carried out with the aid of an omegatron mass spectrometer to determine the purity of hydrogen evolved from a titanium hydride source. Curves of the ion current versus mass‐to‐charge ratio are shown for the system, before, during, and after bakeout as well as during the running of the generator. The generator, after moderate processing, is found to yield hydrogen gas that is 97% pure. The impurities found are water vapor, methane, and ethane. An explanation for the presence of these impurities is offered.