Developing energy markets have placed added pressure on the efficient, carbon neutral generation of hydrogen. Current hydrogen production technology, the steam reforming of methane, is limited in its deployment. On-site hydrogen production for fuel cell technology requires a mobile hydrocarbon source, such as a liquid, rather than a gas that must be piped to a reforming station. Liquid hydrocarbon fuels (such as iso-octane) can be converted to hydrogen and then to electricity with an efficiency that exceeds combustion generators. Reforming reactors, like the autothermal reformer (ATR), are capable of producing hydrogen and carbon monoxide with a higher theoretical efficiency than current steam reforming technology. However, carbon buildup (coking) of these reactors is a major problem, as it causes catalyst deactivation, pressure drops, and non-isothermal reactor conditions. The mechanism of coke formation is studied here with the aid of TGA/FT-IR analytical techniques. In addition, reaction mechanisms are derived from reaction product information (gathered from the FT-IR) and compared with the experimental coking rate (data from the TGA) to quantify the viability of the proposed mechanisms.