This book describes the hydrogen fuel generation from water via photoelectrochemical process. It elaborates the theory and fundamental concepts of photoelectrochemistry to understand the photoelectrochemical process for water splitting to generate hydrogen fuel. The book further deliberates about the hydrogen as a futuristic chemical fuel to store solar energy in the form of chemical bonds and also as a renewable alternative to fossil fuels. The book establishes the need for hydrogen fuel and discusses the standards and practices used for solar driven photoelectrochemical water splitting. It also discusses the current and future status of the nanomaterials as efficient photoelectrodes for solar photoelectrochemical water splitting. The book will be of interest to the researchers, students, faculty, scientists, engineers, and technologists working in the domain of material science, energy harvesting, energy conversion, photo electrochemistry, nanomaterials for photo-electrochemical (PEC) cell, etc.