The effect of the addition of an ionic liquid DEME center dot TFSI to an electrolyte solution of Mg(HMDS) 2-MgCl2 in THF was studied electrochemically and spectroscopically. Reversible magnesium deposition/dissolution was achieved with the DEME center dot TFSI-modified electrolyte. This electrolyte shows higher ionic conductivity, and a linear relationship was observed between the ionic conductivity and the concentration of DEME center dot TFSI in THF solution of Mg(HMDS) 2-MgCl2. Mg-Mo6S8 coin cells have also been successfully cycled using Mg(HMDS) 2-MgCl2 electrolyte with the addition of DEME center dot TFSI. Raman and NMR spectroscopy suggest that DEME center dot TFSI facilitates magnesium deposition/dissolution by improving ionic conductivity of the electrolyte. (C) 2017 The Electrochemical Society. All rights reserved.