Hydrogen isotope retention and its removal in/from a plasma-facing wall and structural materials have been recognized as key issues for fusion reactor from the viewpoints of operational safety and environmental preservation. Baking and/or a glow discharge are possible effective methods to remove hydrogen isotopes from materials. To investigate the absorption and desorption characteristics of hydrogen isotopes in structural materials, a glow discharge apparatus with twin chambers (Glow-1, 2) made with stainless steel was provided. The sample tip can be moved between the Glow-1 chamber and Glow-2 chamber without exposing it to the air. The controlled infrared (IR) heating device was installed in the Glow-1 chamber to heat the sample tip. Results of absorption and desorption by glow discharge, and the thermal desorption by IR heating are analyzed. No oxides of hydrogen isotopes were observed in these experiments. Most gases are retained near the solid surface and are desorbed at a low temperature below 150 °C. The activation energy was estimated to be about 50 kJ/mol.