BaCe0.9Y0.1O3 and Ba0.95M0.05Ce0.9Y0.1O3 (M = Sr or Ca) oxides were synthesized by sol-gel methods in presence of citric acid (optionally with HO(CH2)(2)OH or ethylenediaminetetraacetic acid) at 600-1200 degrees C. The oxides showed isometric particles (50-100 nm). The partial replacing Ba with Ca or Sr resulted in an increase in elec. cond. in H-2(-) contg. atm. The Ca-contg. oxide was recommended as an electrolyte in electrochem. devices.