New ammonium salts of dithiophosphoric O,O'-diesters have been obtained by simple and convenient (one pot) methods of synthesis from white phosphorus (P4), elemental sulfur, alcohols, phenols (including hydroxyethylated nonylphenols), and amines. It has been revealed that the ammonium salts of O,O-dialkyl dithiophosphoric acids obtained are effective inhibitors of carbon dioxide corrosion (protective effect Z = 90-99%) and hydrogen sulfide corrosion (Z = 88-89%) of a mild steel. It has been shown that the inhibitory activity against carbon dioxide corrosion depends on neither theamine nature nor the chain length of the alkyl substituent in the ester group and the protective effect in the case of hydrogen sulfide corrosion depends on the nature of the reactant alcohol or amine and may slightly decrease (by 10-15%). An advantage of these inhibitors is that their protective effect in carbon dioxide corrosion is enhanced with temperature (30-80A degrees C), rather than decreases.