The dynamical behaviour of shock waves at high Mach numbers in dissociated oxygen, during a sequence consisting of a diffraction over a compression corner, the subsequent motion through a constant area tube and a final diffraction over an expansion corner is described in some detail. This type of configuration is required to generate a corner-expansion flow over a wall model in a shock tube by means of a liner. The diffraction over the compression corner was found to yield an interesting irregular Mach reflection phenomenon, brought about by a substantial modification of the flow pattern through the internal energies connected with the high density ratios obtained. The initial diffraction results in a strong distortion of the shock front. Some aspects of the subsequent decay of this disturbance towards the stable i.e., plane configuration were investigated. It was found that a very pronounced decrease in stability occurs at high Mach numbers, illustrated by a slow decrease of the axial extent of the shock shapes. Some evidence was obtained in support of the observations made by Bowman on the existence of two distinct shock-distortion regimes. The investigation of the expansion-corner flows were mainly concerned with the effects of the shock distortion on the flow uniformity in cases where the disturbances had not yet fully decayed on arrival at the corner, for example, in some of the recent corner-expansion work done by Drewry. A qualitative assessment shows that the disturbing influence on that investigation was minor. The repercussion on future corner-expansion work in ionized argon was shown to be even less. (Author).