Heat transfer and pressure measurements were made on a model of the United States Space Shuttle Orbiter in the University of Queensland's T4 shock tunnel at three angles of attack, with stagnation enthalpies which varied by a factor of 11, from 2·1 MJ/kg to 23 MJ/kg and normal shock Reynolds numbers which varied by a factor of 38, from 2·1 x l04 to 8·l x 105. Leeward pressure results were obtained for comparison with flight data and equilibrium calculations, but the majority of the experiments were conducted to investigate the heat transfer distributions around the shuttle model. Both the windward and leeward heat transfer results exhibit the onset of transition to turbulent flow. The leeward results are compared with flight data as well as with conventional wind tunnel data, and are used to establish trends associated with variation in the major flow and geometry parameters. It was found that although high enthalpy effects could be important, Reynolds number effects played a dominant role in determining the flow.