The results of aero-thermal analysis of hypersonic flow over a cylinder is presented in this paper. The flow regimes in hypersonic flow is rarefied and the continuum concept becomes invalid. The Direct Simulation Monte Carlo (DSMC) is a particle simulation method suitable for the analysis of rarefied flow. In this work DSMC simulation is carried out using an open-source code dsmcFoam available in OpenFOAM tool kit. The code has been validated by solving supersonic flow over a flat plate for which results are reported by Bird[1]. The hypersonic flow around a cylinder has been solved for different Knudsen number. The complex flow phenomena are analyzed and discussed.