operation of cone-shaped anode-supported segmented-in-series solid oxide fuel cell (SIS-SOFC) stack directly on methane is studied. A cone-shaped solid oxide fuel cell stack is assembled by connecting 11 cone-shaped anode-supported single cells in series. The 11-cell-stack provides a maximum power output of about 8 W (421.4 mW cm(-2) calculated using active cathode area) at 800 degrees C and 6W (310.8 mW cm(-2)) at 700 degrees C, when operated with humidified methane fuel. The maximum volumetric power density of the stack is 0.9 W cm(-1) at 800 degrees C. Good stability is observed during 10 periods of thermal cycling test. SEM-EDX measurements are taken for analyzing the microstructures and the coking degrees. (C) 2010 Elsevier B.V. All rights reserved.