Formation behavior and structure of newly established anodic films grown on magnesium and AZ alloys were studied in organic electrolyte containing 1 mol dm(-3) triethylamine / ethylene glycol solution with varying water content. The growth behavior and appearance of anodic films were significantly affected by the water content. In the region between 10 and 40 % of water content, compact barrier-type films were obtained regardless of substrate purity. The surface appearance of obtained films was transparent and enamel-like, which was different from those formed usually in aqueous solutions. In addition, these films possessed a high order of resistance to corrosion. In the case of electrolyte containing water below 10 % or above 50 %, the appearances were yellowish white and whitish gray, respectively. The composition of anodic films determined by FT-IR and GD-OES analysis showed the incorporation of organic substance (carbon, nitrogen, oxygen) into the film. The incorporation behavior of organic species was also changed by water content and the amount of incorporated organic species increased with decreasing water content in the electrolyte.