The high-resolution O 1s spectra presented in Fig. support the above observations. The component at 529.9 eV represents Me-O (Me: Mg and Mo) , which dominates at the surface at low Li content and is displaced by hydroxides for AZ31-12Li with Me-OH:Me-O ratio changing from 0.55:1 to 1.22:1 (Table ). The overall observation from the XPS data backs up the electrochemical studies, confirming the higher corrosion susceptibility of the alloys with larger lithium additive, where the passive film is replaced by non-stoichiometric corrosion products (primarily magnesium hydroxides).