Steam electrolysis by solid oxide fuel cell technology, known as SOEC, is considered the most efficient and cost effective option for hydrogen production from renewable sources. By using proton-conducting electrolyte, the SOEC operating temperature can be reduced from over 800^oC to below 600^oC. Technical barriers associated with the conventional oxygen-ion conducting SOECs, such as hydrogen separation from water, oxidation of steam electrode, and instability of oxygen electrode, can be largely mitigated. In this report, an intermediate temperature (400-600°C) electrolysis technology was developed where a novel proton-conductor and a triple-conducting oxide were used as the electrolyte and anode, respectively. The electrolysis cell demonstrated excellent performance and durability at intermediate temperatures, promising a new prospective for next-generation steam electrolysis.