Surface characterization of the corrosion products formed on the surfaces of rapidly solidified Mg based EA55RS (Mg-5 wt% Al-5 wt% Zn-5 wt% Nd) extrusion immersed in a 3% NaCl solution saturated with Mg(OH)(2) has been carried out using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surfaces of both pristine and corroded samples have been found to consist mainly of Mg(OH)(2) and MgO. XPS and AES results show that Nd and Zn are not present on the surfaces of either pristine or corroded samples and depth profiling using SIMS shows that there is depletion of Nd on the surfaces.