Internal partial oxidation reforming of butane and steam reforming of ethanol were investigated using microtubular solid oxide fuel cells (SOFCs) supported on nickel-gadolinia doped ceria (Ni-GDC) anode for portable power sources in an emergency situation and mobilities such as vehicles, robots and drones. At oxygen/carbon (O/C) ratio of 1.0, which is a coking condition in the equilibrium, the Ni-GDC anode deteriorated for 28 h by internal partial oxidation of butane at 650 ^oC. However, power generation was also impossible after 8 and 79 h at S/C = 1.0 and 1.5, respectively, by internal steam reforming of ethanol in spite of no carbon deposition condition in the equilibrium at 650 ^oC. Power can be generated over a period of more than 100 h at O/C = 1.5 in butane and at S/C = 2.0 in ethanol. The O/C and S/C ratios are significantly important to prevent carbon deposition on the Ni-GDC anode for internal partial oxidation reforming of methane and steam reforming of ethanol in SOFCs.