Experimental studies were performed using a pilot-plant scale McInnis-Bischoff variable throat venturi scrubber using operating variable ranges that are normally encountered with industrial size units. The investigation involved the examination of pressure drop as a function of various liquid-to-gas ratios, throat gas velocities and throat area. Two hundred and five separate runs were carried out by measuring pressure drop by varying the throat gas velocity, and the liquid loading. A better understanding of single-phase and two-phase flow losses in variable throat scrubber was achieved during this study. The Rothfus et al. correlation for single-phase flow in annuli has been extended to low (L＇/D)(eq) values for velocities in the range of 60-120 m/s. This extended correlation was essential for the prediction of two-phase frictional losses for all the models tested using the McInnis-Bischoff variable throat venturi scrubber data. The simplified empirical correlation, Delta P-TP = -Delta P-SP + 3.16 x 10(-2) (L/G) - 24.52 where the pressure drop expressed in ems of water was obtained for the prediction of two-phase pressure drop at various liquid-to-gas ratios and throat velocities in the McInnis-Bischoff scrubber.