Copper is commonly regarded to be immune to corrosion in deaerated deionized electrolytes. The present work shows that, in the absence of hydrogen, copper will corrode on the order of 1 nm/day in deionized water with an O-2 concentration on the order of, or less than, 1 ppb. While a corrosion rate of this magnitude can normally be neglected, it may be catastrophic for nanoscale copper structures utilized in emerging applications to enhance energy transport at the solid-electrolyte interface, such as in cooling advance electronics. This conclusion is supported by a set of experimental and analytical studies that encompass impedance spectroscopy, slow-scan linear sweep voltammetry, thermodynamic calculations for the environment under study, and kinetic simulations. The studies provide a comprehensive insight on details of the corrosion mechanism for copper in deaerated water. (C) 2013 The Electrochemical Society. All rights reserved.