Trimolybdenum phosphide is a binary inorganic compound of molybdenum metal and phosphorus with the chemical formula .
Trimolybdenum phosphide can be obtained via electrolysis of a melt mixture of molybdenum hexametaphosphate with molybdenum(VI) oxide and sodium chloride.
Trimolybdenum phosphide forms grey crystals of tetragonal crystal system with space group I4. It is insoluble in water. Trimolybdenum phosphide becomes superconducting at 7 K.
Trimolybdenum phosphide can be used as a catalyst for electrocatalytic processes. It can also be used in accumulators.