Steam electrolysis using SrZr(0.9)Y(0.1)O(3-alpha) (SZY-91) electrolyte was investigated. Different electrode materials, i.e., porous platinum, Sr(0.5)Sm(0.5)CoO(3) (SSC-55) for the anode and nickel for the cathode were examined in order to achieve better energy performance. The electrodes had poor electrode activity when platinum was used for both the anode and the cathode, while the SSC-55 anode displayed significantly low overpotentials and the nickel cathode exhibited low overpotentials upon the introduction of an SrCe(0.95)Yb(0.05)O(3-alpha) (SCYb) Interlayer. Moreover, a partial substitution of cerium for zirconium in the strontium zirconate electrolyte, i.e., SrZr(0.5)Ce(0.4)Y(0.1)O(3-alpha) (SZCY-541), was found to be effective for improving the current efficiency of the hydrogen evolution rate. Accordingly, the cell SSC-55 vertical bar SZCY-541 vertical bar SCYb vertical bar Ni exhibited much higher energy efficiency for the steam electrolysis than the Pt vertical bar SZY-91 vertical bar Pt cell. (C) 2008 International Association for Hydrogen Energy, Published by Elsevier Ltd. All rights reserved.