Molybdenum trioxide is used to manufacture molybdenum metal, which serves as an additive to steel and corrosion-resistant alloys. The relevant conversion entails treatment of MoO3 with hydrogen at elevated temperatures: MoO3 + 3 H2 → Mo + 3 H2O
It is also a component of the co-catalyst used in the industrial production of acrylonitrile by the oxidation of propene and ammonia.
Molybdenum trioxide has also been suggested as a potential anti-microbial agent, e.g., in polymers. In contact with water, it forms H+ ions that can kill bacteria effectively. However, the issue of keeping the catalyst clean in an environment that would exploit such antimicrobial properties has not been explored.