A lateral jet in a supersonic crossflow creates a highly complex three-dimensional flow field which is not easily predicted. The aim of this research was to assess the use of a RANS based CFD method to simulate a lateral jet in supersonic crossflow interaction by comparing the performance of available RANS turbulence models. Four turbulence models were trialled in increasingly complex configurations; a flat plate, a body of revolution and a body of revolution at incidence. The results of this numerical campaign were compared to existing experimental and numerical data. Overall the Spalart-Allmaras turbulence model provided the best fit to experimental data. The performance of the lateral jet as a reaction control system was assed by calculating the force and moment amplification factors. The predicted flowfield surrounding the interaction was analysed in detail and was shown to predict the accepted shock and vortical structures. The lateral jet interaction flowfield over a body of revolution was shown to be qualitatively the same as that over a flat plate. An experimental facility was designed and manufactured allowing the study of the lateral jet interaction in Cranfield University’s 2 ½” x 2 ½” supersonic windtunnel. The interaction was studied with a freestream Mach number of 1.8, 2.4 & 3.1 and over a range of pressure ratios (50≤PR≤200). Levels of unsteadiness in the interaction were measured using high bandwidth pressure transducers. The level of unsteadiness was quantified by calculating the OASPL of the pressure signal. OASPL was found to increase with increasing levels of PR or MPR and to decrease with increases of Mach number. The levels of unsteadiness found were low with the highest levels found downstream of the jet.