La(Sr)Ga(Fe,Mg)O-3 exhibited the high oxide ion conductivity and the electrical power generating property of SOFC single cell using La0.7Sr0.3Ga0.7Fe0.2Mg0.1O3-delta (LSGFM) electrolyte was investigated in this study. The transport number of oxide ion is almost 0.8 in LSGFM and so open circuit potential (OCV) is as low as 0.8 V OCV was strongly affected by anode materials and the highest OCV was achieved on Ni-Fe bimetallic anode. The extremely high power density was achieved by using LSGFM for electrolyte of SOFC. The maximum power densities of the cells can be elevated by coating with oxide ion conductor film at anode side. The maximum power density increased in the following order for coating film: LSGM > SDC > YSZ. The maximum power density of 197 and 100 mW/cm(2) can be achieved at 873 and 773 K, respectively, when LSGM film deposited on the anode side of LSGFM. Therefore, LSGFM can be used as electrolyte of SOFC operating at intermediate temperature. (c) 2006 Elsevier B.V All rights reserved.