This proposal supports development of multi-physics finite-element model of the performance of a metal-hydride hydrogen storage tank. While simple to use, a massive metal-hydride hydrogen storage tank is internally complex because of the need to remove the heat of absorption and supply the heat of desorption. The interaction of enthalpy flow, mass flow and hysteresis causes the local hydrogen content to differ greatly from the global average owing to temperature gradients. We propose to use volume-resolved neutron powder diffraction to measure the spatial distribution of phase proportions that develops in response to changes in supply or demand pressure. The data will be used to thoroughly test the ability of the FEA model to calculate the spatial distribution of hydrogen content in a metal-hydride tank based on an alloy exhibiting significant pressure hysteresis and/or plateau slope.