We show that resistive heating of the metal surface of a supersonic molecular beam nozzle is very effective in converting CO2 diluted in H2 to CO and H2O via the reverse water–gas shift (RWGS) reaction at temperatures that preclude simple pyrolysis. The conversion of CO2 to CO, referred to as “RWGS yield,” exceeds 80% at nozzle temperature above 1000 K, with a detectable methane byproduct. The stainless-steel surface of the nozzle appears to facilitate the reaction as a heterogeneous catalyst. Reaction yield increases with nozzle temperature and when the gas mixture contains a significant excess of H2, while decreases with increasing nozzle stagnation pressure. The inverse dependence of the reaction on stagnation pressure is used to propose a reaction mechanism based on redox mechanisms for high temperature RWG catalysts in the forward and reverse directions. Additional kinetic control over the mechanism is afforded by adjusting reactant partial pressures, residence times inside the nozzle reactor, and nozzle temperature, highlighting this method’s utility in screening heterogeneous catalysis reactions with fine control over mass flow rates, pressure, and temperature. This supersonic reaction technique can also facilitate reactions with surface-generated gas-phase radicals, followed by rapid desorption and cooling of the intermediate products. The results of this study, therefore, present a route to efficient, high pressure, inline catalysis as well as a method to rapidly assess the viability of new catalysts in development.