In this paper the passive oxide film modification of an AISI 304L stainless steel by a surface treatment carried out with an atmospheric-pressure plasma jet (APPJ) generated by air was analysed. In addition, the influence of the surface modification on the corrosion properties of this steel was estimated. The passive surface film of stainless steel was examined by X-ray photoelectron spectroscopy (XPS) and by Secondary Ions Mass Spectrometry (SIMS) depth profiling before and after the plasma treatment. Potentiodynamic anodic polarization tests and electrochemical impedance spectroscopy (EIS) measurements were employed to investigate the effects of the surface plasma treatments on the corrosion protection properties of the plasma treated samples. The plasma treatments allowed the formation of a passive layer, that exhibits higher corrosion resistance than the native film. Time of treatment influenced both the …