A technique is described by which the flow properties in a conventional diaphragm shock tube were determined from an analysis of the particle trajectories within the flow. The particle trajectories were obtained by high‐speed photography of smoke tracers placed at 10 cm intervals along the 8 m length of the tube. The subsequent analysis gave the space and time variation of pressure, density, velocity, and temperature of the gas throughout the tube, for a shock of intermediate strength. The results are compared with those made using other measurement devices for pressure and density and it is concluded that the technique gives the flow properties to an accuracy of about 5%. The technique also revealed some aberrations of the flow which had not been detected by other means.