A reference electrode for use in molten salt systems is described. It consists of a porcelain capsule conductive to sodium ions, containing a silver electrode immersed in a melt of silver chloride and sodium chloride. The electrode is reversible to sodium ions. It is stable, reproducible, and temperature‐reversible and can be used at temperatures 400° to 500° higher than can similar electrodes made of glass. The capsule‐type construction prevents the salt inside the electrode from contaminating the melt under study. Electrodes made from specially prepared porcelains and also from a commercial porcelain were used. Data are presented on the resistivity of the specially prepared porcelains and on the mechanism of conduction by the porcelain.