Molybdenum compounds are chemical substances that contain the element molybdenum, which is a transition metal. These compounds can exist in various forms, including oxides, sulfides, and halides. They are often used in industrial applications, such as catalysts in chemical reactions and as additives in steel production to enhance strength and resistance to corrosion. In addition to their industrial uses, molybdenum compounds play a role in biological systems. Some organisms require molybdenum as a trace element for enzyme function, particularly in processes like nitrogen fixation. Overall, these compounds are important in both technology and biology.