It is demonstrated that the oxidation behaviour of chromium was significantly different according to the temperatures, i.e. 800, 900, and 1000 degreesC. Under isothermal condition, the formation of a chromia scale on pure PM chromium follows parabolic kinetics, indicative of a diffusion-controlled growth mechanism. At each temperature the mass gain curves showed some discontinuities that can be explained by the formation of cracks, that gives a direct access to non-oxidized metallic surfaces. Nevertheless, under the experimental conditions, chromium was able to form a rather protective oxide scale, preventing the underlying substrate against severe corrosion by a healing process. Cross-section examinations revealed that under the oxide layer a nitrogen-rich sub-surface layer was formed in the substrate. X ray diffraction results prove that due to inward diffusion of nitrogen, a solid solution of nitrogen in chromium was formed, which finally reacts with each other forming chromium nitrides CrN and Cr2N. The presence of this nitrogen rich layer changes the metallic matrix hardness and then a decrease of the oxide scale adherence was observed.