Laboratory studies of hydrogen and deuterium retention/desorption and hydride formation in liquid lithium samples exposed to those gases at 200°C and 400°C are reported in the present work. Two distinct absorption phases with different kinetics are observed and discussed. The calculated absorption rate constants show a preferential absorption of D2 over H2 in clean lithium and a faster absorption of H2 for predeuterated samples. First dynamic experiments on Li samples preimplanted with H2 and D2 show no evidence of isotope exchange at least up to 500°C. TDS of Li samples exposed to H/D and of Li/LiH powder mixtures present desorption peaks at ∼500°C, well below the observed decomposition temperature for LiH powder and no precipitated LiH is detected after the complete evaporation of Li (∼700°C). Also, preferential release of H2 retained in the solution with respect to the formation of LiH is deduced from the desorption spectra.