AbstractBACKGROUND: Ejectors have excellent mass transfer characteristics with energy efficiency and can be used in place of conventional countercurrent systems, namely, packed bed contactors as well as venturi scrubbers, cyclones and airlift pumps. Although a number of papers have been published in the recent past, none of them provides a theoretical basis for the prediction of gas phase holdup. In this work an attempt has been made to develop a theoretical basis for predicting gas phase holdup based on first principles using Nguyen and Spedding's distribution function (Co) and initial value parameter (B).RESULTS: In the present work, measurements and correlations are reported for the gas holdup and energy dissipation in a liquid‐gas ejector. The holdup data have been correlated using the theoretical models proposed by Nguyen and Spedding, with an estimated initial value parameter B and the distribution function Co. The throat and diffuser loss coefficients were found to be constant up to a gas/liquid flow ratio of 1.6 and then it was found to be a function of area ratio, physical properties and gas holdup.CONCLUSIONS: The present proposed correlations for gas phase holdup and energy dissipation, Emix, should be useful for the efficient design of co‐current ejectors for gas‐liquid contacting, in particular for the removal of CO2 from natural gas, since the viscosity and surface tension ranges covered in the present study are essentially those encountered in amine–carbon dioxide systems. Copyright © 2008 Society of Chemical Industry