Earth-abundant transition metals - such as iron, copper, manganese, cobalt, and nickel - offer viable alternatives to expensive noble metals commonly used in the fields of catalysis, environmental science, materials chemistry, pharmaceuticals, and sustainable energy. The book presents a comprehensive compilation of recent studies that leverage the potential of these metals across various industries. Keywords: Catalysts, Solid Propellants, Therapeutics, Solar Cells, Supercapacitors, Chemical Sensors, Water Treatment, Hydrogen Production, Hydrogen Evolution.