The diffusion coefficients (1.0 x 10(-12) -4.0 x 10(-11) m(2) s(-1)) and its activation energy (103.7 +/- 9.5 kJ/mol) for tritium in intermetallic compound beta-LiAl are determined at temperatures from 699 to 886 K. Though the present result for the diffusion coefficient is almost the same as that reported earlier, the activation energy turns out nearly twice of that (64.9 +/- 3.8 kJ/mol) reported earlier. On the basis of the crystal structure and defect structure, the large activation energy of this study suggests that tritium diffuses interstitially and is impeded by an attractive interaction with lithium atoms in lithium sublattices. (c) 2006 Elsevier B.V. All rights reserved.