The redistribution of chloride and sodium ions after the NaCl-induced atmospheric corrosion of Mg alloy AM50 was investigated by means of Time-of-Flight Ion Mass Spectroscopy (ToF-SIMS). The samples were exposed at 4 and 22 degrees C in the presence of 400 ppm CO2. The results confirm the presence of less conductive electrolyte, and thus, less movement of ionic species (including sodium and chloride) in the electrolyte layer formed on the surface of samples exposed at the sub-zero temperature. Besides, ToFSIMS analysis showed the presence of an Al-containing surface film formed on the alloy surface after exposure at high relative humidity. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.