Sorption behavior of tritium to isotropic graphite is discussed including solubility, diffusivity in the bulk of isotropic graphite and sorption capacity of hydrogen isotopes on the surface of isotropic graphite. The solubility and the diffusion coefficient of hydrogen isotopes in the graphite are obtained using the breakthrough method in the temperature range of 673–1273K and the activation energy of diffusivity is about 100kJ/mol. The sorption capacity of tritium on the graphite surface is also obtained by the breakthrough method using tritiated water in nitrogen gas flow. Tritium is captured on the graphite surface by isotope exchange reaction between tritium in gas flow and hydrogen in hydroxyl group on the graphite surface.These hydrogen atoms in hydroxyl group can easily exchange with other hydrogen isotopes in gas flow though they cannot be easily released from the graphite by drying or evacuating.