The anodic behaviour of platinum in sodium chloride solution has been studied. It has been shown that below about 1·6 V, chlorine evolution occurs on a clean platinum surface but above this potential, a surface oxide develops on the eloctrode and a rapid potential jump occurs. The kinetics involved in the oxidation of chloride ions and subsequent discharge of chlorine are influenced by ions other than Cl −. New values for α, i o and η a have been obtained, and the influence of a Cl − and pH has been demonstrated.