Molybdenum and its compounds (oxides, sulphides, carbides, nitrides, selenides, molybdates and molybdenum complexes) have a number of applications in alloys, catalysts, electrochromics, sensors, capacitors, batteries, solar cells and so on. Promising works on their nanostructures have been reported as a means to enhance the performance of materials. The present book is an edited volume on molybdenum and its compounds in different applications. There are chapters concentrating on molybdenum and its alloys, molybdenum oxides, molybdenum sulphides, molybdenum carbides, molybdenum nitrides, molybdenum selenides, molybdenum blues, Keplerate-type molecular spheres, molybdenum complexes and molybdates.