The diffusivity and the migration energy of H in Al at high temperatures have been found to be consistent with low-temperature experiments when the possibility of temporary localization of the H atoms at thermal equilibrium vacancies is taken into account. The migration energy in the perfect lattice is determined to be 0·52±0·07eVand DHo≈ 8 × 10−5m2s−11. These data are in excellent agreement with theoretical and experimental results. From these data the H-vacancy binding energy is determined to be 0·43±0·07eV.