PURPOSE: To produce a β-alumina electrolyte raw material composed of nearly single phase with easy low-temperature calcination process by adding acetic acid to a mixed solution containing alkoxides of Al and Na at a specific ratio and hydrolyzing with a methanol-diluted water to obtain a gel.

CONSTITUTION: A mixed solution of an aluminum alkoxide and a sodium alkoxide is prepared at an Al:Na atomic ratio of (6-10):1. The mixed solution is mixed with acetic acid and then hydrolyzed in one stage by adding methanol- diluted water in an amount not less than the amount necessary for hydrolysis, preferably about ≤4 times the necessary amount. The gel produced by this process is aged, dried at about 70°C and calcined at a low temperature (about ≤1200°C, preferably about 1000-1100°C). A single-phase β-alumina electrolyte raw material composed of fine particles having diameter of about ≤0.5μm can be produced by this process.