This book presents state-of-the-art contributions related to advanced structural characterization techniques in the field of clean energy materials with particular emphasis on solid oxide fuel cells and hydrogen storage materials. It describes several diffraction and spectroscopic techniques for the investigation of both average and local structures with several examples of the most recent materials for clean energy applications. It is the first authoritative collection of contributions on the importance of the application of the most advanced structural techniques to shed light on the properties and mechanisms of materials currently investigated for the use in alternative energy devices. The book provides key techniques for ex situ and in situ investigation of clean energy materials and, hence, is an essential guide for researchers working on the structural analysis of advanced materials.