For high-speed air-breathing propulsion, limitations on the usage of liquid hydrocarbon fuel-air mixtures result from their long ignition delays and slow combustion rates. Furthermore, vehicle heat loads generated from high speed flight are excessive and their management becomes an important challenge. In this respect, the use of multifunctional nanostructured materials that can be dispersed in liquid fuels has been considered in recent years as a means to enhance the cooling capacity, the combustion performance, and recombination kinetics of dissociated products. This work thus aims to understand the fundamental effects of graphene-based nanostructured materials on the thermal decomposition of a fuel under supercritical conditions. The supercritical pyrolysis of dodecane containing functionalized graphene sheets (FGS) without or with platinum nanoparticles was studied in a high pressure flow reactor over the temperature range of 480 - 530 °C, at a constant pressure of 4.75 MPa, and at a constant flow rate of 5.0 ml/min. With the addition of the platinum-decorated FGS particles, it was found that conversion rates are higher than those of pure dodecane. Selectivities in product yields with and without the graphene additive were also different as a function of temperature, concluding that the activity of the particles on the product distribution could be controlled.