Different Kinds of Food Contains Monopotassium Phosphate Monopotassium phosphate (MKP) is the inorganic compound with the formula KH2PO4. Together with dipotassium phosphate (K2HPO4.(H2O)x), it is regularly used as a fertilizer, food additive, and buffering agent. The salt often cocrystallized with the dipotassium salt as well as with phosphoric acid. It is also known as potassium dihydrogen phosphate (KDP), or monobasic potassium phosphate.