A computational study has been done to assess the effectiveness of porous medium in control of normal-shock-wave/boundary-layer interaction at transonic speeds with a view towards application in aircraft wings. Passive control is achieved via re-circulation inside the porous medium, which weakens the shock structure, and hence reduces the wave drag. The study has been done for a Mach 1.3 normal-shock-wave/boundary-layer interaction on a at plate in the presence of a porous medium beneath the region of interaction. The domain used for the computations is adapted from a novel experimental setup, due to Holger Babinsky and his group at Cambridge University, that is capable of stabilizing a normal shock over a control region for fixed inlet parameters. The dependency of the control effectiveness on dimensions of the cavity (length, depth) and porosity has been studied. It is observed that whereas the cavity length has a strong effect on the reduction in total drag, the effects of depth and porosity are less pronounced. The computations are done as steady state RANS calculations using Menter’s k – ω/k – ϵ model for turbulence closure. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.