We have investigated the oxidation of austenitic stainless steels AISI SAE: 304, 316 and 317, at temperatures of 700 to 750°C in an atmosphere approaching 100% of steam, and in a time range of 10 to 1000h of exposure. The purpose is to check the quality of austenitic steels and studying the morphology, composition and structure of the phases of the layers formed on the oxide scale samples by scanning electron microscopy (SEM), X-ray analysis energy dispersive (EDAX) and X-ray Diffraction (XRD), respectively. Just as well, has been performed at different times, a systematic study of Thermogravimetry of the samples oxidized, which was observed that the AISI 304 steel had the lowest mass gain and the AISI 316 steel had the higher mass gain respect to the three steels of the work. Additionally we carried out a theoretical study of thermodynamic simulation of steam oxidation of three steels, under the same experimental conditions and by the Thermo-calc program. In the oxidized steels have been checked the presence of oxide phase structures such as Fe2O3, the protective mixed spinels Fe3O4 and Cr2NiO4, and mixed oxides of type (CrxxFey)2O3, (Fe,Cr,Mn)3O4 and Ni6MnO8. Finally, it was discusses a possible mechanism of formation of oxide layers of the samples tested.