X-ray absorption fine structure (XAFS) analysis was performed on the CuCl2 cathode in Li/CuCl2 battery with LiPF6/methyl difluoroacetate (MFA) electrolyte to investigate the valence states of Cu during discharge/charge. X-ray absorption near edge structure (XANES) spectrum indicated that the Li/CuCl2 battery can discharge and charge reversibly. The disproportionation side reaction is confirmed to occur during charging. The side reaction, known to induce battery self-discharge, can be suppressed if reaction Cu + LiCl -> CuCl + Li+ + e(-) proceeds completely, which may be accomplished by using a more homogeneous composition in the cathode. (C) 2016 The Electrochemical Society. All rights reserved.