Germanium oxide (GeO2) was electrochemically reduced to Ge in molten CaCl2-NaCl at 600 degrees C, and the electrochemical behaviors of the electrolytic Ge were studied in the same electrolyte. From the cyclic voltammetry study, three alloying-dealloying processes were found to be related with electrochemical alloying of Ca2+ ions in the electrolytic Ge and stripping of Ca out from the Ca-Ge alloys. Galvanostatic charge-discharge technique was employed to study the specific capacity of electrolytic Ge for storing Ca, as well as the cyclability of the alloying-dealloying processes. At a charge-discharge rate of 2 A g(-1), the gravimetric capacity of the electrolytic Ge is 553 mAh g(-1). Overall, the results show that Ge is a promising material for Ca storage. (C) 2016 The Electrochemical Society. All rights reserved.