An environment-friendly phosphate chemical conversion (PCC) coating has been deposited on novel LAT971 (Mg-9 wt% Li-7 wt% Al-1 wt% Sn) and LATZ9531 (Mg-9 wt% Li-5 wt% Al-3 wt% Sn-1 wt% Zn) alloys for improving their corrosion resistance. A dense and homogeneous flower like morphology (similar to 30 mu m thick) was observed on the PCC coated Mg-Li based alloys. The presence of calcium hydrogen phosphate hydrate, tricalcium phosphate and trimagnesium phosphate were confirmed from the X-ray diffraction and X-ray photoelectron spectroscopy analysis. A lower corrosion current density of 6.74 x 10(-7) mA/cm(2) and 5.39 x 10(-7) mA/cm(2) was obtained for PCC coated alloys in 3.5% NaCl aqueous solution than that of uncoated LAT971 (0.82 mA/cm(2)) and LATZ9531 (0.34 mA/cm(2)) alloys, respectively, which offers corrosion protection efficiency of > 99%. Electrochemical impedance spectroscopy (EIS) has revealed that the inner PCC coating (at coating/substrate interface) delay the direct contact between electrolyte and substrate, which offered higher charge transfer resistance (> 4 orders of magnitude) than that of uncoated alloys. Thus, the PCC coating provides an effective corrosion protection to the ultra-lightweight LAT971 and LATZ9531 alloys surface and may be helpful in proving good anchoring with the top organic coatings or paints. (C) 2018 Elsevier B.V. All rights reserved.