A formation process of amorphous layers on steel surfaces have been tested for two systems: NaH2PO4-H3PO4-NaClO3-H2O (a) and NaH2PO4-H3PO4-Na2H2P2O7-NaClO3-H2O (b). Total P2O5 concentration varied from 1,2 to 7,0 g/dm(3). It has been stated that the P2O5 pyre form presence enables decreasing the effective reaction temperature to 30 degrees C and increasing in coating weight. Favourable effect of disodium pyrophosphate on a corrosion resistance in the salt spray test results has been confirmed.