By an extension of the ideas embodied in the single‐pulse shock tube, a technique has been developed which allows the direct measurement of recombination rates of many atomic species at high temperature. In the present technique, the expansion chamber is located a few tube diameters from the shock tube end plate rather than at the high‐pressure end as in the conventional single‐pulse shock tube. A cylindrical diaphragm, lying flush with the inside diameter of the tube, is used to control the time of initiation of an expansion wave. Experimental observation has shown that the present technique increases the gas expansion rate by an order of magnitude in comparison with the conventional single‐pulse shock tube. The one‐dimensionality of the flow at the shock tube end wall has also been investigated. The technique developed, in conjunction with the spectroscopic means of observation, was employed to gain preliminary measurements of the recombination rate of atomic chlorine.