Spectroelectrochemistry (SEC) is a powerful yet usually inexpensive technique which yields mechanistic (“-chemistry”), energy-relevant (“-electro-”) as well as electronic structure information (“spectro-”). The whole range of the electromagnetic spectrum can be employed, from X-ray absorption to NMR spectroscopies. SEC is used in areas such as analytical, materials, supramolecular, surface, polymer, organic, organometallic, inorganic and biochemistry. The principles of the method and practical guidelines are presented here by relevant examples and this book will appeal to scientists from all chemical sub-fields who have a basic understanding and experience in electrochemistry.