Research on ''clean energy materials'' is an important and growing area in the field of materials science, much due to the need of developing cleaner and more sustainable sources of energy, which is one the the major challenges in the 21st century. The performance of alternative energy technologies depends on the properties of their component materials. For the development of next-generation devices, the discovery and optimization of new materials are critical to future breakthroughs. This depends on a better understanding of the basic science that underpins applied research, but such understanding is often lacking. In view of this lack of knowledge, this proposal aims at elucidating key fundamental properties, such as local structure, structural disorder and conduction mechanisms in two classes of energy-related materials, namely proton-conducting oxides, targeted as electrolytes for intermediate-temperature fuel cells, and ''complex'' metal hydrides, targeted as media for on-board hydrogen storage. The goal is to develop an atomic-scale understanding of the proton (hydrogen) diffusion mechanism and apply this knowledge to the rational design of new materials with higher proton conductivities or more favorable hydrogen sorption properties. The primary tools to this end involve the use of neutron and synchrotron x-ray scattering techniques, available at international large-scale research facilities, and vibrational spectroscopy (Raman and infrared), available at the host organisation, Chalmers University of Technology.