Manganese(II) phosphate, also called Manganese diphosphate or Manganese phosphate tribasic, is an inorganic compound with the chemical formula Mn₃(PO₄)₂. It has industrial importance as a constituent of manganese based phosphate conversion coatings.

Manganese phosphate can  be used for coatings (which are processed as described above). These coatings are useful for protection against corrosion and wear over time, due to their toughness. Manganese phosphate coating can often be found in the oil and gas industry, firearms and ordnance, aerospace, gears and bearings, and in marine equipment. They are also common in engines, screws, nuts and bolts, and washers.