A high work capacity radial inflow turbine with a known performance base was modified to accept a combination of moveable nozzle sidewalls, diffusing or acceleration rotor inlet ramps and rotor exit restriction rings. The overall performance of this variable geometry turbine was measured at constant speed and pressure ratio for thirty-one (31) different test configurations. Data were obtained over a nozzle area range of 50 to 100 percent of maximum.The nozzle area was varied by moving both the forward and rearward sidewalls of the nozzle assembly. A comparison of the overall performance of this concept with a variable stagger angle vane concept shows that the use of a moveable sidewall for area control is a viable alternative option. Air leakage between the nozzle vane and moveable sidewall were found to affect performance significantly and are a factor to be minimized in any given practical application.This paper presents the results of the experimental investigation and provides an aerodynamic data base for a variable geometry radial turbine turbine utilizing a moveable sidewall nozzle.