The study examines the capability for reduction of the resonant pressure fluctuations in supersonic flow over an open rectangular cavity using repetitively pulsed energy deposition, computationally. The simulations are performed for the cases both with and without energy deposition for the unsteady flow over a three-dimensional cavity at a free stream Mach number of 1.5. The Reynolds-averaged compressible time dependent Navier Stokes equations in three dimensions are solved using the flow solver GASPex. The k-ω turbulence model is used. A Gaussian temperature profile is utilized to model the energy pulse assuming the density within the spot is initially uniform. The results indicate that energy deposition reduces the pressure fluctuations changing the flow structure within the cavity. ©2008 TIBTD Printed in Turkey.