The air self-entrainment by a liquid jet is investigated in an industrial scale ejector-venturi scrubber. A mathematical model based on steady-state macroscopic mechanical energy balances is formulated and arranged in order to obtain simple equations useful for design purposes. Experiments are carried out in order to evaluate empirical values for the frictional coefficients. Gas entrainment and void pressure measurements are presented by using different geometric combinations for the venturi tube throat and the pressure-swirl atomizer used for inducing the gas flow rate. (C) 2003 Elsevier B.V. All rights reserved.