Surface cleaning is performed under an Ar-1 vol.% N2 gas mixture using either a dielectric barrier discharge (DBD) process or a microwave post-discharge process at atmospheric pressure. Naturally oxidized iron foils are treated by these two processes to remove a contamination layer. The time evolution of XPS peaks of the C(1s) components at 286.6 eV (CN containing species) and at 288.3 eV (carbonyl-like species like ketones) using the DBD treatment and of the N(1s) component at 399.4 eV (NC groups) does not agree an exponential decay function resulting from a simple etching mechanism by nitrogen active species. In the post-discharge process, FeOOH (O(1s)—532.7 eV) groups are completely removed. N in NaNO3 (407.3 eV) is found on the surface of the iron foil. After approximately 1 min, the surface state of iron foils cleaned by either process is the same, showing a comparable ability for cleaning.