[en] Neutron quasielastic scattering experiments on liquid lithium (at 500 and 830 K) and a lithium-hydrogen melt (99 at.% Li⁷ and 1 at.% H at 830 K) have been performed. The characteristics of the diffusion mobility for lithium and hydrogen atoms have been extracted from the experimental results and analyzed with the use of phenomenological and theoretical models. The self-diffusion coefficient in liquid lithium obtained for both temperatures is in agreement with values in the literature. The mechanism of hydrogen diffusion mobility in liquid lithium is discussed. It has been concluded that the hydrogen in the liquid lithium exists and diffuses in the form of the hydride LiH