ZnCl2 is one of the dominant aggressive species in waste incinerators or other advanced combustion power generationsystems. In this study, the influence of minor amount of gaseous ZnCl2 on the corrosion behavior of pure iron wasexamined at 600～800℃ in a pure oxygen environment. The corrosion rate usually increased markedly with increasingtemperatures at a fixed ZnCl2 content or with increased ZnCl2 contents at a constant temperature. The corrosionproducts were composed of a thin outer layer of ZnFe2O4 spinel and an inner zone with a much thicker layer ofFe2O3, which exhibited a serious separation from the matrix. Moreover, a molten FeCl2 layer was observed at thescale substrate interface. The accelerated corrosion of pure iron was attributed to the existence of FeCl2 with lowmelting point on the metal surface, which destroyed the cohesion and adhesion of the oxide scale. The results arediscussed in relation to the thermodynamic factors and the presence of volatile compounds in the reaction system.