[en] In an attempt to determine the diffusivity of tritium in lithium aluminate, we have performed isothermal anneal tests on single crystal samples (approximately 1.5 mm dia.). Large single crystals were used to minimize the contributions from desorption. Diffusion kinetics become more dominant as the crystal radius increases due to the decreasing surface area to volume ratio. However, the release may still be in the mixed diffusion-desorption regime which would make obtaining the rate constants from the time dependence of the tritium release difficult. Therfore, we have decided to section the samples and determine the diffusivity from the tritium concentration profile within the sample. In addition, in an attempt to understand the effects of impurities on the tritium transport, we have studied the tritium profiles in pure and Mg doped (0.3%) LiAlO₂