Abstract: The hydrodynamics of perform trays were studied using air-water system in a column with a 1200 x 400mm rectangular cross section to determine the effect of tray geometrical parameters and operating conditions on the pressure drop, entrainment and weeping. Geometrical variables and operating range were mainly as follows: slot widths, 3, 3.5, 4, 4.5 and 4.7mm; tray free areas, 9.9, 12.3, 14.9 and 15.4%; deflector widths, 150, 200, 250 and 300mm; tray spa-cings, 400, 500, 600, 700 and 800mm; liquid flow rates per unit weir length, 20, 30, 45 and 60m3/m.h; and superficial gas velocities, 0.60 to 2.8m/s. Experimental data were correlated and correlations were presented for calculating the pressure drop, entrainment and liquid weeping. Furthermore, based on the experimental results for the entrainment and weeping from the tray,the expressions were given also to predict the upper limiting hole velocity at which the entrainment from the tray is 10%, the lower limiting hole velocity at which the liquid weeping from the tray is 5%. In addition, the effect of inlet weir on the weeping were tested and a simiempirical model was derived for the inlet weir design. These correlations, as mentioned above, can be applied to the design of perform trays.