Examination of the surface of Mg alloys by Raman spectroscopy was reported in based on the Raman peak at 3652 cm -1 corresponding to the A1g O-H stretching vibrations in Mg(OH)2. In our experiments, the analysis of Mg-containing corrosion products was performed focusing on the low-wave number region (200-1200 cm -1 ), where both Mg(OH)2 and Mo-rich species can be analyzed . Raman spectra of all alloys after exposure to 0.05 M NaCl solution without inhibitor for 1 h were similar and showed two characteristic Raman bands at 280 and 443 cm -1 , corresponding to Mg(OH)2 . After 24 h of the exposure to uninhibited solutions resulted in the appearance of the Raman band at 1094 cm -1 , which was assigned to the formation of magnesium or lithium carbonates on the surface, probably by the reaction with CO2 dissolved in the electrolyte . Moreover, we cannot exclude the formation of surface carbonate layers already after 1 h of exposure. However, the thickness of these layers might be not enough for Raman analysis . Its position is very sensitive to changes in the coordination geometry, the chain length, and the hydration degree of molybdate species . This approach was also utilized in our previous publications . After 1 h of exposure, Raman spectra of all alloys contain Raman bands at 1004, 996, and 265 cm -1 , which are typical for hydrated molybdenum(VI) oxide, MoO3(H2O)3 . The Raman band at 1110 cm -1 can be assigned to polyoxomolybdate species or MoOx oxides, which can be formed due to the reduction of the oxidization state of some Mo . Raman bands at 942 cm -1 originate from Mo O - . Raman bands at 321 and 911 cm -1 were assigned to dimolybdates MoO - . Importantly, no Raman signal assigned to reduced phases of Mo(IV) compounds was observed after 24 h of exposure. The phase composition and amount of Li in the alloys have a significant effect on the shape of the obtained spectra. First, XPS spectra shown in Fig. reveal a progressive negative shift of the Mg 1s peak location from 1303.6 eV (for AZ31-4Li) down to 1303.2 eV (for AZ31-12Li), a feature revealing that the alloy surface is covered with the growing amount of Mg hydroxide that probably displaces or covers dense inner MgO layer . At the same time, the Mg moieties share at the surface increases rapidly, tripling its value. . Its share is the highest in the case of the AZ31-4Li and AZ31-8Li alloys, reaching approx. 12 at.% and drops down to 5.3 at.% for theAZ31-12Li alloy (Table ). Additionally, other molybdenum species, Mo(V) and Mo(IV) have been detected in the composition of the surface layers, which share seems to be less affected by the lithium content.