Degradation of component materials such as gas or steam turbines under high temperature environments has been one of severe problems due to not only high temperature corrosion or oxidation but also erosion caused by the impact of metallic oxide particle formed in upstream systems. It is important to know mechanical properties and adhesion of oxide films formed on metal surfaces at high temperatures, in order to estimate degradation rates and to select high resistant materials against high temperature erosion corrosion. We have tried to examine these properties of oxide films formed on carbon steel, and to establish degradation models of the oxide films. The phenomenon of high temperature erosion corrosion caused by solid particle impact was also discussed.