Electrochemical impedance spectroscopy (EIS), open circuit potential and pH changes were used to examine the corrosion of magnesium 4% yttrium alloy (Mg4Y) with and without a silane-epoxy-coating (SEC) in a stirred 0.154 M NaCl solution at 37 degrees C. For a good quality SEC we find a relatively low non-Faradaic resistance of 266 Omega cm(2). The quality of the SEC was affected by the curing temperature. In this article we compare the electrochemical measurements taken during corrosion of bare Mg4Y. Mg4Y with a SEC that remained intact, and a SEC that did not protect the Mg from corrosion. (C) 2012 Elsevier Ltd. All rights reserved.