The advantages of a flat-tube solid oxide fuel cell (FT-SOFC) include easy sealing, low stack volume and low resistance to current collection. Because the performance of the FT-SOFC is closely linked to the interior hydrogen channel design, this paper studied various channel designs using a numerical approach. Ordinary FT-SOFCs have many channels with small cross-sectional areas. Unfortunately, this design makes it possible for the sealing material to block the channel entrance. Furthermore, it is difficult for the hydrogen to be evenly distributed under this type of design. To overcome these problems, a new design was developed to reduce the number of channels and increase the cross-sectional area. Contrary to expectations, the numerical approach applied here revealed that new design resulted in poor hydrogen transport into the support region and an average current density of 2846.7 A/m(2), lower than that of the traditional design. Another design with a gradually increasing width from inlet to outlet was applied to increase the performance, maintain the mechanical strength and reduce the pressure drop of SOFCs. This design improved the average current density to 3135.4 A/m(2). However, the cell performance with this channel design decreased significantly when the channel inlet became too narrow or when the outlet became too wide. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.