Performance of a two phase downflow bubble column fitted with an ejector has been evaluated with respect to depth of penetration of the jet in the liquid column and entrainment of secondary air. Experiments were carried out with a column of 51.6 mm i.d. and. five different nozzles. Three systems, namely air-water, air-kerosene and air-paraffin were used. Correlations have been developed for predicting the gas entrainment ratio and the jet coefficient for momentum transfer during penetration as functions of the physical and dynamic variables of the system.