Used as a catalyst in petroleum refining and chemical synthesis, particularly in hydrodesulfurization processes to remove sulfur from fuels. Employed in the production of molybdenum metal and ceramics due to its thermal stability. Acts as a corrosion inhibitor in cooling water systems and metalworking fluids. Common reagent in analytical chemistry for the determination of phosphates, silicates, and arsenates, forming yellow heteropoly acid complexes. Applied in electroplating baths to deposit molybdenum coatings for wear resistance. Used in agriculture as a micronutrient source of molybdenum in fertilizers for leguminous crops to support nitrogen fixation. Also utilized in flame retardants and smoke suppressants in plastics and textiles.