A direct approach for determining the tray and point efficiencies of an industrial-scale distillation tray is proposed. The stripping of isobutyl acetate from an aqueous solution with air was used, which is a manageable and nonhazardous method applicable for performance tests in large hydraulic column mockups. This work represents the first application of this system in the case of tray columns exemplified for a sieve tray. A column of 800 mm internal diameter was used for conducting the stripping experiments. The distribution of isobutyl acetate in the liquid phase on the tray was obtained via liquid sampling at several deck positions and UVspectroscopy analysis. A definition for the liquid-side tray efficiency in weeping conditions is proposed together with an experimental approach for determining tray and point efficiencies in such conditions. The derived efficiency data show good agreement with the model predictions and correlations.