A novel way to quantify polarization losses at an organic liquid electrolyte/single ion conductor interface is presented. Different concentrations (9.2 M, 0.4 M, 0.6 M, 0.8 M, 1 M) of LiPF6 in EC:DEC (1:1), 1 M LiPF6 in DMSO, and 1 M LiPF6 in PC were used as organic electrolytes in the study. Lithium Ion Conducting Glass Ceramic (LICGC), commercially acquired from Ohara Corporation (1 in. x 1 in., 150 mu.m thick) was used as the single ion conductor (SIC). A custom Li-Li symmetric diffusion cell was designed for this study. For a given electrolyte of known composition, constant current cycling experiments were first performed in the absence of the SIC. Thereafter, SIC was incorporated in the cell such that it was sandwiched between two electrolyte chambers. The polarization loss from the cell was then extracted from these two sets of experiments after accounting for the Ohmic drop in the SIC and concentration polarization effects in the liquid electrolyte for a given current density, using a mathematical model. Results suggest that liquid electrolyte/SIC junction polarization could be significant. Such polarization losses will lead to a decrease in the cell voltage at high currents in next generation Li-S and Li-O-2 cells. (C) 2014 The Electrochemical Society. All rights reserved.