In this research the oxidation of ASTM A335 P92 steel and the effect of 40% K2SO4 - 60% NaCl salt mixture at temperatures of 500oC to 700oC in intervals of 50°C with exposure times of 1,3,10, 30,100 and 150 hours were evaluated using the standard standardized by the European Federation of Corrosion. Metallographic analysis and hardness analysis were performed before and after the test to identify the possible structural change; evidence of x-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS) were performed to determine the corrosion products present in the steel. By SEM-EDS analysis it is shown that corrosive species such as Cl--, SO4-- do not react with the alloying elements of steel. It was also noted that the oxide layers formed showed stability, and good adhesion which confirms the oxides protection on the metal. The “gained weight by salts deposition” curves showed a parabolic behavior, typical of high temperature materials.