Etched beta"-alumina ceramic electrolyte

A process for producing a cationically-conductive ceramic electrolyte of symmetric polarization which comprises providing a cationically-conductive ceramic electrolyte of asymmetric polarization, said electrolyte ranging in composition from an alkali metal beta"-alumina phase to a mixture of alkali metal beta"-alumina phase and up to about 50% by volume of alkali metal beta-alumina phase based on the total volume of the electrolyte, said alkali metal being selected from the group consisting of sodium, potassium, lithium, mixtures thereof and alloys thereof, and etching the surface portion of said ceramic electrolyte with phosphoric acid to produce said cationically-conductive ceramic electrolyte of symmetric polarization, said phosphoric acid having a concentration of P.sub.2 O.sub.5 which etches said ceramic body, said etching having no significant deleterious effect on said ceramic electrolyte.