Tritium release from 1.5 mm diameter Li2ZrO3 spheres has been examined in post-irradiation annealing tests, to support the Canadian sphere-pac breeder-blanket concept. Rapid tritium release was observed over the complete temperature range studied, 573–723 K. The tritium was recovered primarily in the tritiated water (HTO) form, except when He-1% H2 sweep gas was used and the temperature was ≥673 K. Hydrogen added to the sweep gas increased the release rate. The features of the tritium release curves from the on-line ionization chamber indicate some unexplained tritium release behaviour, not previously seen with LiA1O2 or Li2O.