Eco-friendly vanadia based chemical conversion coating was applied for improving the corrosion resistance of a newly developed magnesium AZ31 HP-O alloy. The effect of vanadia solution concentrations (10, 30 and 50 g/l) and pH on the corrosion protection performance of magnesium substrate were investigated. EIS and cyclic voltammetry techniques were used to evaluate the electrochemical behavior in 3.5% NaCl. Results showed a marked increase in the localized corrosion resistance after applying vanadia surface treatment of 50 g/l as measured by EIS and polarization techniques. The optimum conditions to obtain protective coatings for AZ31 HP-O were determined. The surface morphology, composition and microstructure of conversion coatings were followed by AFM, SEM-EDS and macroscopic imaging techniques. (C) 2010 Elsevier Ltd. All rights reserved.