The electrochemical behaviour of 1024 mild steel electrodes was investigated in the presence of 0.05-0.5 M disodium phosphate aqueous solution, in the pH range 8.4 to 9.7 and from 5 to 50 degrees C. Bicarbonate solutions were also considered for comparison. Voltammograms were obtained with a rotating gold ring steel disc electrode, and the effects of the phosphate concentration, pH, electrode rotation speed, anodic potential limit and temperature were considered. For potential sweeps in the anodic direction in phosphate solutions, the voltammograms display an oxidation peak current at low potentials and a passivity region at higher potentials. The rate-determining step of the oxidation peak current was also investigated. The oxidation current in the passivity region is virtually independent of the applied potential, temperature, pH and phosphate concentration.