One major unsolved problem for the introduction of hydrogen into the global energy system is the storage of hydrogen. The present proposal concerns metal hydrides based on complex hydrides, an important group of metal hydrides where improved hydrogen stor age properties are anticipated. The focus is on using high resolution X-ray synchrotron diffraction to understand kinetic, thermodynamic and morphological properties that must be overcome to develop complex hydrides into hydrogen storage materials of real interest for the transportation sector.