This paper reports the development of intermediate temperature-operating solid oxide fuel cell stacks using anode-supported planar cells with LaNi0.6Fe0.4O3 (LNF)cathode. We developed metallic separators with radial gas flow channels and an anode seal structure. To achieve good power-generating characteristics, we propose two cathode contact methods. According to a performance evaluation at 800 degrees C, power density of 0.5 W cm(-2) is obtained at the current density of 1.0A cm(-2) when operating with a sufficient fuel amount, and power conversion efficiency of over 50% LHV is obtained at the current density of more than 0.2A cm(-1) when operating at a high fuel utilization rate. (c) 2008 Elsevier B.V. All rights reserved.