The oxidation behavior of SUS430 metallic interconnects for solid oxide fuel cell (SOFC) is investigated. Different reductive atmospheres are applied on one side of the interconnect with air on the other side to simulate the environment in a SOFC stack. The oxidation behavior under dual-atmosphere differs from that in a single air atmosphere. A thicker Mn-Cr spinel layer is formed on CH4/air dual atmosphere sample while Fe2O3 nodules are found on 5% H-2/air sample, and a continual Fe2O3 layer is formed for H-2/air sample. It can be concluded that the anomalous oxidation behavior of the interconnect is induced by a high concentration of H-2 at the fuel side, which is caused by hydrogen diffusion from the fuel side to the air side across the interconnect. This results in the formation of cationic vacancies which accelerate the diffusivity of iron cations. For the fuel side of the dual atmosphere, the oxides morphologies on the interconnect surface are related to the oxygen partial pressure. Fibrous shape oxides are formed at low oxygen partial pressure and fine grain shape at high oxygen partial pressure. The anomalous oxidation processes in dual atmosphere are further investigated by means of marker experiments using an inert Au marker. (c) 2017 The Electrochemical Society.