In this paper, a new concept of diesel fuel processing is introduced for the stable operation of solid oxide fuel cells (SOFCs). High temperature operation of SOFCs can lead to the capability of internal reforming with fuel flexibility. SOFCs can directly use CH(4) and CO as fuels given sufficient steam feeds due to catalytic reaction on the SOFC anode. However, heavier hydrocarbons than CH(4), such as ethylene, ethane, propane, etc., induce carbon deposition on the Ni-based anode of SOFCs. In the case of an ethylene steam reforming reaction on the Ni-based catalyst, the rate of carbon deposition is faster than it is when hydrocarbons, including aromatics, are used. Hence, the removal of light hydrocarbons (over C(1)-hydrocarbons), especially ethylene, with the reformate gases of heavy hydrocarbons (diesel, gasoline, kerosene, and JP-8) is important for stable operation of SOFCs. A new methodology, called the "post-reformer", is introduced for removing the light hydrocarbons (over C(1)-hydrocarbons) with the reformate gas stream. The CGO-Ru (3.0 wt.%) catalyst was selected as the post-reforming catalyst because it shows high selectivity for removing light hydrocarbons (over C(1)-hydrocarbons) and achieving the high reforming efficiency. The diesel reformer and post-reformer are continuously operated for about 200 h in an integrated mode. The reforming performance did not degrade, and light hydrocarbons (over C(1)-hydrocarbons) in the diesel reformate were completely removed. (C) 2010 Published by Elsevier B.V.