Stable, reproducible, and well-defined reference electrodes are vital for accurate quantification of battery material properties and physical mechanisms. Repeated studies have shown sodium metal to be an unreliable reference electrode material in nonaqueous solvents. This work evaluates several alternative reference electrode chemistries including sodium-tin alloy, nickel hexacyanoferrate and carbon. Of the systems tested, non-aqueous silver/silver-ion reference electrodes were shown to yield the most stable and reproducible voltage measurements. (C) The Author(s) 2019. Published by ECS.