Tritium release behavior for thermal neutron-irradiated Li0.17Pb0.83 eutectic alloy was studied. Main tritium release peak was observed in the temperature just a little higher than melting point in a thermal desorption spectrometry (TDS) experiment. Most of tritium release from Li0.17Pb0.83 eutectic alloy was found to be governed by diffusion process from the results of isothermal annealing experiments. Tritium diffusivity in a liquid state of Li0.17Pb0.83 eutectic alloy was evaluated to be D = 4.7 × 10-8 exp(-0.13 eV/kT) m2 s-1 . Tritium diffusivity was increased by the phase transition of Li0.17Pb0.83 eutectic alloy from a solid state to a liquid state, resulting in the sharp tritium release peak that appeared in TDS spectrum. In addition, about 4% of tritium was trapped in Li0.17Pb0.83 eutectic alloy as Li-T bond.