Studies of rubidium selenate with secondary phase of RbOH under humidified reducing atmosphere

► Degradation of Rb2SeO3 and Rb2SeO4 to form RbOH provide protonic conductivity. ► The conductivity increases by increasing temperature. ► The highest conductivity value of 2.01·10−4 S cm−1 is observed at 317 °C. ► The work may state conductivity rise in solid acid electrolytes upon decomposition.