Objective To investigate the oxidation behavior of T92 steel in 90% Ar + 10% H₂O atmosphere at 750℃ . Methods High-temperature oxidation experiments were conducted in a tube furnace. The morphology, microstructures and composition of oxide films were examined by SEM / EDS and XRD. Results The main oxide was composed of Fe₂O₃ and FeCr₂O₄at the early oxidation stage in high-temperature water vapor environment. Then at the further oxidation stage, Fe ions diffused outwardly, resulting in accelerated oxidation. The oxidation scales consisted of two layers, a porous Fe₂O₃ outer layer and a Cr-rich inner layer. Voids existed in both layers. Some cracks between the inner and outer layers were observed. Conclusion A protective Cr-rich oxide film was not formed in the early oxidation stage. Therefore, T92 steel suffered from oxidation in water-vapor atmosphere at high temperature.