[en] A technique has been developed for cleaning and conditioning low- and medium-energy accelerators by alternating a glow discharge using hydrogen gas and a glow discharge using oxygen gas. The study was initiated using a 2.5-MeV Van de Graaff accelerator. It has since been used on both lower-energy (down to 10 keV) and higher-energy (up to 10 MeV) accelerators with equal effectiveness. In the development stage, the conditioning time for attaining the nominal maximum voltage was reduced from about ten days using pumping and voltage conditioning to one day using the glow discharge technique. After a glow discharge conditioning sequence, the 2.5-MeV accelerator could be operated effectively at energies to 3.4 MeV. In addition, the accelerator tube life was found to increase significantly over the expected lifetime. This technique is described and safety considerations are discussed