Book excerpt: Over the past two decades, the rapid development of nanochemistry and nanotechnology has allowed the synthesis of various materials and oxides in the form of nanopowders making it possible to produce new energetic compositions and nanomaterials. This book has a bottom-up structure, from nanomaterials synthesis to the application fields. Starting from aluminum nanoparticles synthesis for fuel application, it proposes a detailed state-of-the art of the different methods of preparation of aluminum-based reactive nanomaterials. It describes the techniques developed for their characterization and, when available, a description of the fundamental mechanisms responsible for their ignition and combustion. This book also presents the possibilities and limitations of different energetic nanomaterials and related structures as well as the analysis of their chemical and thermal properties. The whole is rounded off with a look at the performances of reactive materials in terms of heat of reaction and reactivity mainly characterized as the self-sustained combustion velocity. The book ends up with a description of current reactive nanomaterials applications underlying the promising integration of aluminum-based reactive nanomaterial into micro electromechanical systems.