Carbon deposits are the most probable mode of deactivation for solid oxide fuel cell (SOFCs) using methane or higher hydrocarbons as fuel. The deposition of various carbon allotropes on the anode material was studied under dynamic and isothermal conditions. The results show methane dissociation on Ni-YSZ (nickel-yttrium stabilized zirconia) under the temperature-programmed mode in three general steps. Under isothermal conditions, various carbon species formed depending on the temperature. The presence of amorphous, filamentous, pyrolitic, and graphitic carbon allotropes was determined by quadrupole mass spectroscopy (QMS), X-ray crystallography, field emission scanning electron microscopy (FE-SEM), and infrared spectroscopy (IR). Carbon allotropes were subsequently oxidized in the atmosphere with 20.0 vol% and 0.5 vol% of oxygen in argon. Complex oxidation mechanisms were detected and discussed.