The interaction of a microwave-generated plasma with a hemisphere cylinder at Mach 2.1 is simulated. The theoretical model is the unsteady threedimensional Euler equations for a multi- species reacting gas. The thermochemistry model for air incorporates 23 species and 238 reactions. The initial condition for the simulation is the steady flow past the hemisphere cylinder.A 9 GHz microwave pulse of 1.2 μs duration is focused upstream of the blunt body shock on the hemisphere cylinder centerline. The high temperature plasma region generated by the microwave pulse is convected to the hemisphere cylinder and interacts with the blunt body shock resulting in the momentary formation of a recirculation region and reduction in surface pressure on the hemisphere cylinder centerline. The computed surface pressure shows good agreement with experiment.