Molybdenum diphosphide is a binary inorganic compound of molybdenum metal and phosphorus with the chemical formula .
Molybdenum diphosphide can be obtained by heating molybdenum with red phosphorus in a closed tube at 550 ðC:
Molybdenum diphosphide forms black crystals of orthorhombic crystal system with space group A2<sub>1</sub>am. It is insoluble in water. It decomposes when heated, releasing molybdenum monophosphide and white phosphorus:
Molybdenum diphosphide can be used as a catalyst.