Strain imaging of electrochemical behavior of a solid electrolyte Cu2S in switching devices for nonvolatile memories is presented. The precipitation and dissolution of Cu, and the nonstoichiometry changes cause changes in volume. Strain imaging we have proposed detects the volume changes through the surface displacements using scanning probe microscopy and provides high resolution images. We observed the distributions of the electrochemical reactions in Cu2S and located the Cu bridges causing switching. (C) 2011 Elsevier B.V. All rights reserved.