A new facility to study the interaction of hydrogen isotopes with nuclear fusion-relevant first wall materials, and their retention and release, has been produced. The new facility allows for implanting a range of gases into samples, including tritium. An accurate study of isotope effects, such as the isotopic exchange in damaged microstructure, has previously been difficult due to a background signal of light hydrogen. This new capability will allow virtually background free measurements using tritium and deuterium. The design and build of this facility are described and commissioning results are presented. Within the UKAEA-led tritium retention in controlled and evolving microstructure (TRiCEM) project, this facility is used for the comparative study of deuterium retention in self-ion irradiated Eurofer steel and Fe–Cr alloy. Self-ion bombardment with energies of 0.5 MeV is used to mimic the defects created by neutrons in fusion power plants and the created traps are then filled with deuterium in the new facility. Implanted samples are analysed using thermal desorption spectrometry (TDS), secondary ion mass spectrometry (SIMS), and transmission electron microscopy. Results on the total deuterium content as a function of time, TDS spectra and SIMS analysis are presented. A comparison of the results for Eurofer and Fe–Cr revealed several differences. While some of them may be due to experimental details like different time delays between exposure and analysis, others, such as deuterium retention as function of dose, might be genuine and require further studies.