Molybdenum diphosphide is a binary inorganic compound of molybdenum metal and phosphorus with the chemical formula MoP₂.

Molybdenum diphosphide can be obtained by heating molybdenum with red phosphorus in a closed tube at 550 °C:

Molybdenum diphosphide forms black crystals of orthorhombic crystal system with space group A2₁am. It is insoluble in water. It decomposes when heated, releasing molybdenum monophosphide and white phosphorus:

Molybdenum diphosphide can be used as a catalyst.