The thermal release behavior of tritium produced in neutron-irradiated Li2O, γ-LiAlO2, Li2SiO3, Li4SiO4, Li2ZrO3 and Li8ZrO6 crystals was studied with emphasis laid on the tritium release kinetics. The tritium produced in these oxidic ceramic materials irradiated with neutrons was released mainly in the chemical form of tritiated water (HTO) when heated in a vacuum. The HTO(g) release process of oxidic ceramic materials was explained by a mixed regime effect where the bulk diffusion of T+ and solid-surface reaction of OT− compete for overall control of the release rate. The observed order of tritium diffusivity in these materials was D(Li8ZrO6) − D(Li4SiO4) >D(Li2O) >D(Li2ZrO3) >D (Li2SiO3) >D(γ-LiAlO2). The tritium diffusivity increased with an increase of the lithium-atom density in these materials.