The corrosive effects developed on Fe-9Cr-1Mo steel in a typical combustion environment were evaluated. For this, steel samples were submitted in a pirotubular horizontal boiler, through the design of a coupon holder. With the experimental conditions characterized, the theoretical corrosion products were simulated; which showed similarity with SEM-EDS and DRX analysis, in the formation of hematite, magnetite and chromite. On the other hand, the oxide layers morphology deposited on the substrate, indicated the appearance of multiple efforts in them: cracks, pores, voids and detachments were observed. To complement these observations, the kinetic study was carried out, which allowed to determine a semi-protective behaviour from the oxide layers formed on Fe-9Cr-1Mo steel; where the diffusive processes are partially reduced. Finally, only oxidation and some localized nitridation could be identified. Carburization could not be identified due to the high oxygen potentials in the environment, and to the short-selected exposure times.