[en] Pulsed nuclear magnetic resonance methods have been used to investigate the properties of various metal-hydrogen systems including ZrH/sub x/, ScH/sub x/, NbH/sub x/, VH/sub x/ etc. For pure dihydride-phase samples of ZrH/sub x/, the spin-lattice relaxation time T₁ has been measured as a function of temperature in the temperature range from 10 K to 1300 K at 12.2 MHz and 40 MHz. These measurements show that the activation energy E/sub a/ for hydrogen diffusion first increases smoothly from 0.57 eV/atom at x = 1.58 to 0.63 eV/atom at x = 1.93 and then increases quite rapidly near the stoichiometric limit, reaching 1.06 eV/atom at x = 1.98. T₁ measurements at temperatures below 300 K reveal that the d-band electronic states are split due to the Jahn-Teller effect. For ZrH/sub x/ samples doped with paramagnetic impurity ions (Mn, Cr, Fe), an additional spin-lattice relaxation rate R/sub 1p/ was observed. The rate R/sub 1p/ increases in the sequence Fe-Cr-Mn and also increases sharply with increasing hydrogen concentration in each case. The former result is consistent with the observation that the tendency towards localized-moment formation in Zr increases in the same sequence, whereas the latter may be accounted for by the anti-trapping behavior of these impurities. For dilute solid α-phase ScH/sub x/, we measured T₁ of both ¹H and ⁴⁵Sc as a function of temperature to investigate hydrogen diffusion. The activation energy E/sub a/ = 0.54 eV/atom and attempt frequency ν₀= 1 /times/ 10¹⁴ Hz were obtained. The absence of a prefactor anomaly in this dilute system is consistent with the hypothesis that such anomalies in other systems may result from repulsive particle-particle interactions at the saddle point. 95 figs