We have studied the dynamics of the H-2 loaded THF (tetrahydrofuran) clathrate hydrate by using an inelastic neutron scattering technique At 2 K a well defined single peak indicative of the ortho (J = 1) to para (J = 0) hydrogen transition is observed at 13 6 meV The neutron spectrum undergoes two distinct changes as the temperature increases First additional peaks appear from splitting of the rotational transition above 10 K Upon further heating a quasi elastic neutron scattering (QENS) signal due to hydrogen molecular diffusion through the THF hydrate crystalline lattice grows significantly above 65 K These results indicate that H-2 molecules trapped inside the THF hydrate crystalline structure undergo two distinct transformations in their dynamical behavior (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved