Composite coatings using pure Al powder blended with alpha-Al2O3 as feedstock were deposited on AZ91D magnesium alloy substrates by cold spray (CS). The content of alpha-Al2O3 in the feedstock was 25 wt.% and 50 wt.%, respectively. The effects of alpha-Al2O3 on the porosity, microhardness, adhesion and tensile strength of the coatings were studied. Electrochemical tests were carried out in neutral 3.5 wt.% NaCl solution to evaluate the effect of alpha-Al2O3 on the corrosion behavior of the coatings. The results showed that the composite coatings possessed lower porosity, higher adhesion strength and tensile strength than cold sprayed pure Al coating. The corrosion current densities of the composite coatings were similar to that of the pure Al coating and much higher than that of bare AZ91D magnesium alloy. (C) 2009 Elsevier B.V. All rights reserved.