The release behavior of tritium from a molten LiF-BeF2 mixture, called flibe, was studied in support of the development of a tritium recovery process. The condensable tritium component in the sweep gas was attributed to TF and the non-condensable component to HT. The isothermal release of each component was analyzed by taking into account the mass transfers and the chemical reactions in the system. It was found that the mass transfer coefficient of TF at the gas-liquid interface was much lower than that of HT. For comparison, the diffusion coefficient of tritium in a molten flibe was measured by a capillary method, and the effective film at the interface was estimated to be ~1 mm thick. The isotopic exchange reaction of TF with H2 was confirmed to occur in the presence of H2, resulting in the HT production. The reduction of TF by the constituents of stainless steel might be responsible for additional production of HT.