Corrosion of ferritic-martensitic steel (FMS) Gr. 91 was performed in static Pb-15.7Li melt at 450 °C for up to 3000 h. Preferential grain boundary corrosion along with a homogeneous dissolution was observed. In addition, Al2O3 was coated to prevent the surface recession of FMS. Al2O3 was deposited on FMS using an electron-beam evaporated physical vapor deposition. The as-coated layer was crystallized through a heat-treatment at above 950 °C for 2 h. The alumina coating layer was very stable and effective to prevent the corrosion of FMS. Although Al2O3 was decomposed in 3000 h, the corrosion barrier survived up to 2000 h even in an oxygen-containing harsh environment.