An experimental study has been made of compressible jet mixing in an axisymmetric ejector of converging-diverging geometry. Three different jet sizes, 0.01, 0.0235, and 0.045 in. diameter were tested with three different mixer sizes, 0.25, 0.286, and 0.36 in. diameter. Jet and mixer combination were tested along with varying jet to mixer distances. The jet pressure varied from 20 to 200 psig, jet mass varied from 0.3 lbm/hr to 10 lbm/hr., and jet temperature varied from 21 to 24 deg. F. The secondary loop pressure varied from 3.7 to 25 psia, secondary mass flow varied from 1 to 70 lbm/hr, secondary loop pressure drop varied from 4 inH20 to 10 inH20, and secondary loop temperature varied same as jet temperature. The mass flow ratio was in the range of 2 to 14. The results were analyzed and compared with the Hickman and Nuckols and Sexton prediction models. The loss factor in Nuckols and Sexton model was adjusted to match the test results. The experimental study helped to more accurately design the ejector for the Liquid Air Backpack (LAB) and Advanced Technology Spacesuit (ATS). Statistical analysis technique was applied to develop prediction models for loss factor and actual and fitted mass factors for a given jet diameter, mixer diameter, secondary loop pressure, and secondary loop pressure drop.