Hydrogen trapping in an Al-2.1 wt% Li alloy aged up to typical stages in the age-hardening curve, has been studied by measuring the tritium release rate after charging. The distribution of hydrogen in the aged alloy has been studied by tritium electron microautoradiography. It has been found that the coherent delta’ precipitate and the incoherent delta precipitate act as a trapping site for hydrogen, while the semi-coherent delta’ precipitate does not trap hydrogen. A dislocation has been found to be capable of trapping hydrogen, while hydrogen trapping by the grain boundary has not been observed.