The design of supersonic turbine nozzles and rotors is discussed and a series of four supersonic turbine nozzles, which is believed to be of a new type, was built and tested. The ratio A/A* between the outlet flow area and the throat area varied between 3.64 and 1. Four axial turbines with these nozzles and with the same rotor were tested over wide ranges of pressure and speed ratios. These turbines were of impulse type. The influence on mass rate of flow and efficiency of Reynolds number and axial distance between stator and rotor is given. Stator and rotor efficiency, Mach numbers, and flow angles, as well as other flow quantities, are obtained by means of a wheel with axial outlet.