To date, conversion of chemical energy to electrical energy for portable power sources has primarily focused on available thermoelectric elements limited to low temperatures and, therefore, low Carnot efficiencies. With advances in thermoelectric (TE) and thermophotovoltaic (TPV) devices allowing higher hot side temperatures, there is an increasing need for small (cm3 scale, O(10–100) W chemical), stable platforms to fully oxidize practical liquid fuels with little pressure drop at high (∼800–1000°C), uniform temperatures. Hybrid heterogeneous/homogeneous (HH) reactors provide a means to achieve this. The heterogeneous nature of HH reactors offers inherent stability against reaction extinction while homogeneous reactions are capable of fully converting the fuel; combined, the net effect of HH operation shows promise to both intensify and stabilize a reactor subject to high throughput and heat losses. In this work, we examine the operation of a dodecane fueled parallel plate microreactor with platinum-coated walls targeted for TPV applications. Increasing the confinement of the reactor increases the rate of heat and mass transport to the catalytic walls and, simultaneously the reactor temperature and homogeneous reaction rates. It is shown that, by tuning the reactor confinement, it may be possible to deliver the high, uniform temperatures required for efficient thermal-to-electric power conversion with low diffusivity tactical fuels. Simplified models provide insight into the thermal behavior of the reactor and the role of homogeneous dodecane decomposition on reactor performance.