Abstract An investigation of the performance of small commercial single and two-stage steam-jet ejectors handling air and steam at temperatures to 1000 F was conducted under the sponsorship of the Heat Exchange Institute. The results of tests are expressed in terms of “entrainment ratio,” which is the ratio of the flow rate of gas at a given temperature to that of the same gas at a base temperature. Entrainment ratio was found to be a linear function of temperature. The test results given appear to be independent of pressure and of design characteristics of the ejectors tested. Therefore the plot of the variation of entrainment ratio with temperature is, within the limits of the test accuracy, thought to be applicable to any ejector system.