An experimental study on the performance of an adjustable ejector is presented. An axial spindle extending into the nozzle is used to change the nozzle throat area to make the ejector adjustable. The variation of operation parameters, such as pressure, temperature, and entrainment ratio, was investigated for several typical spindle positions. The tests observe that when the nozzle throat cross section area of the adjustable ejector was reduced, the entrainment ratio was raised at the expense of the falling of discharge pressure. These characteristics of the adjustable ejector provide potential for a more economical design and operation. DOI: 10.1061/(ASCE)EY.1943-7897.0000058. (C) 2012 American Society of Civil Engineers.