The localized vibrations of hydrogen in various LaNi5Hx samples were studied using inelastic neutron scattering (neutron spectroscopy). The pronounced vibrational peaks obtained for "virgin" strain-free α-LaNi5H0.15 indicate the existence of two different hydrogen sites. During the activation for hydrogen absorption, substantial distortion is introduced into the LaNi5 lattice which is locally probed by the vibrating hydrogen atoms. © 1984.