This book provides an overview of issues pertaining to hydrogen storage materials and applications. It focuses on the materials approach, which is essential to the continuing development and utilization of clean energy systems and fuel cells that use H2as a fuel. The book also summarizes the state of the art in compressed gas and cryogenic storage. It describes a variety of applications, such as engineering applications, mobile technologies, and stationary power applications, to illustrate how the systems under development can be applied to real-life problems.