Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump for pumping hazardous liquids because of its mechanical simplicity, no maintenance, simple control etc. In this study, an experimental setup of SJP was developed in which the mixing section was made transparent for flow visualization. The effect of the mixing section length on the transport process in SJP has been studied using three different lengths of the mixing section (110, 130 and 150 mm). Moreover experiments were performed to study the suction characteristics of SJP at various operating conditions. Better performance was observed in the SJP geometry with shorter length of the mixing section. A new concept of interface vibration process in direct-contact condensation (DCC) of SJP was introduced using the experimental results. An effort has been made to explain the process of DCC in SJP using the concept of interface vibration process. The performance characteristics of SJP have also been studied in the light of interface vibration process in DCC of SJP. (c) 2012 Elsevier Ltd. All rights reserved.