Abstract: The crystal of intermetalic compound β-6LiAl is grown by the Tamman method and is examined by X-ray Laue method. This crystal is a polycrystal containing a few small mono-crystals.The tracer diffusion coefficient of tritium in neutron irradiated β-6LiAl is determined by radiomet-ric method. It is suggested that Arrhenius plots of the diffusion coeffieients tends around 700K,associated probably with the defect structure change.