Ammonium diethyl dithiophosphate or more systematically ammonium O,O′-diethyl dithiophosphate, is the ammonium salt of diethyl dithiophosphoric acid. It is used as a source of the (C₂H₅O)₂PS₂⁻ ligand for preparing dithiophosphate complexes. Some such complexes have use as oil additives. It can be obtained by the reaction of phosphorus pentasulfide with ethanol and ammonia. In crystal structure of this compound the ammonium cation is connected by four charge-assisted N—H···S hydrogen bonds to four tetrahedral diethyl dithiophosphate anions.^[1]

• Dimethyl dithiophosphoric acid
• Zinc dithiophosphate