Advanced Cooling Technologies, Inc. (ACT) has been developing a Swiss-roll type, non-catalytic, thermal partial oxidation JP-8 reformer. The principle is using effective heat recirculation to increase the partial oxidation reaction temperature, which maximizes the H2 and CO yield without using catalyst. The gas phase reaction eliminates catalyst-associated issues, such as poisoning, coking, degradation, etc. Since the process uses only air and JP-8 fuel as the reactants, and is self-sustained (no external energy input), minimum balance-of-plant is required. One challenge of this reforming technology is the “out-of-center” reaction. Due to being highly preheated, the fuel and air mixture from the inlet is auto-ignited before entering the designed center reaction zone. The out-of-center reaction causes low reforming efficiency and potentially damages the inlet channel walls. In the previous study, direct injection of JP-8 fuel into the center reaction zone is able to avoid the out-of-center reaction. However, without proper mixing of fuel and air, the reaction happens in a non-premixed fashion that results in a large amount of soot formation in the reformate. To overcome this issue, a center mixing chamber is designed. JP-8 fuel is directly injected in this mixing chamber and mixed with preheated air before entering the center reaction zone. Experimental results show a significant improvement in the reformate quality after the implementation of the mixing chamber. Test data of syngas (H2 and CO) yield and reforming efficiency (chemical enthalpy in the reformate compared to the parent fuel) are also reported.