The electrolyte material Ce0.85Sm0.15O1.92 (SDC) powders are synthesized by glycine nitrate processes and BaCe0.83Y0.17O3-delta (BCY) powders are synthesized by sol gel processes, respectively. Then SDC BCY composite electrolytes are prepared by mixing SDC and BCY. The SDC and BCY powders are mixed in the weight ratio of 95:5, 90:10 and 85:15 and named as 5395, SB90 and SB85, respectively. The electrical properties of SDC and SDC BCY composites are investigated. The experimental results show that SDC BCY composites exhibit the excellent conductivity and could significantly enhance the fuel cell performances. The behavior that SDC BCY composites display hybrid proton and oxygen ion conduction is substantiated. Among these electrolytes, the maximum power density reaches as high as 159 mW cm(-2) for the fuel cell based on SB90 composite electrolyte at 600 degrees C. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.