The oxygen reduction reaction (ORR) on stainless steel oxides is a complex process that can drive galvanic corrosion on more electrochemically active materials such as aluminum, as well as drive localized corrosion. The local structure of the oxide, including defects and variations in composition and microstructure, determines the catalytic properties of the surface, and importantly this structure changes with potential. At more negative potentials, the partially-reduced surface changes the properties of the oxide. Electrochemical studies of both a stainless steel alloy as well as pure Fe, Cr, and Ni samples are compared to discern the surface species present and their impact on the kinetics for the ORR. Electrochemical impedance spectroscopy is used to probe the changing oxide properties with applied potential. These measurements are supported by surface analytical techniques including X-ray photoelectron spectroscopy to determine oxidation states and composition of the initial oxide and after potential holds, as well as glow-discharge optical emission spectroscopy to depth-profile the distribution of elements at the surface.