The electrochemical properties of the key intermetallic particles that form in commercial Mg alloys are presented. Results were collected via microcapillary electrochemical testing upon bulk intermetallic analogs in dilute chloride solution. The intermetallics investigated were Mg17Al12, Mg2Al3, Mg2Ca, Mg12Ce, Mg12La, Mg3Nd, Mg2Si, Mg24Y5, and MgZn2. It was found that the intermetallic phases, with the exception of Mg2Ca, were more noble than Mg, supporting increased levels of cathodic kinetics; however, the variation in electrochemical response between intermetallics was large in terms of corrosion potential, presence of a passive window, and currents sustained over a range of potentials. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3523229] All rights reserved.