Li/sub 2/O pellets irradiated with thermal neutrons were isothermally annealed to release tritium in a helium atmosphere at temperatures ranging from 673 to 1073 K. The release rates were found to significantly increase at elevated temperatures and to depend on the density of the Li/sub 2/O pellet. The overall diffusion coefficients of the release process were calculated using the cylindrical geometry model for the pellets as D(cm/sup 2/ s/sup -1/)=1.02 x 10/sup -3/ exp(-51.0 kJ mol/sup -1//RT)(90% theoretical density pellets), and D (cm/sup 2/ s/sup -1/)=2.64 x 10/sup -3/ exp(-46.5 kJ mol/sup -1//RT)(ca. 80% T.D. pellets) over the region 773 <= T <= 1073/sup 0/K. The result of the release experiment at 673/sup 0/K sugested that the diffusion rate was controlled by the decomposition of lithium hydroxide on the surface of Li/sub 2/O grains.