Two-cell solid oxide fuel Cell (SOFC) stacks with an anode-facing-cathode configuration were operated in single chamber conditions, i.e., oxygen, methane, and nitrogen mixture. The effect of the distance between two cells on the cell performance was investigated. A single cell consisted of a porous NiO/8 mol % Y2O3-stabilized ZrO2 (YSZ) anode support, a YSZ electrolyte membrane, and a Ce0.8Sm0.2O1.9-impregnated La0.7Sr0.3MnO3 cathode. The experimental result demonstrated that the effect of the distance on the cathode was quite distinct when the distance (D) was equal to 2 mm. The distance effect could be negligible when D was larger than 4 mm. The effects were also varied with the ratio of methane and oxygen (M). An acceptable value of the distance was critical for the operation and performance of the stack. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3196245] All rights reserved.