Hypersonic laminar flow past a rearward facing step has been numerically investigated using computational fluid dynamics (CFD). The flow parameters were : total specific enthalpy h_o ≈7.6 MJ/kg; unit Reynolds number Re ≈1.82 × 10⁶ 1/m ; and Mach number M_∞ ≈7.6. A detailed grid independent study has been carried out to investigate the sensitivity of the surface heat flux in the regions of separation and reattachment. The nature of the flow in the close vicinity of the step is particularly emphasised. The influence of real-gas effects such as the thermal and chemical non-equilibrium are studied using Park's two-temperature model and finite-rate chemistry models respectively. The numerical results are then compared with the available experimental data of surface heat flux measurements.