The combined effect of flow conditions, geometry and physical properties on distillation efficiency of a newly constructed small-size Teflon bubble-cap tray for production of high-purity substances is experimentally investigated. The limits of vapour loading required for a steady hydrodynamic tray operation are found. The results evidence an influence of the liquid entrainment on plate efficiency at elevated superficial vapour velocities and higher downcomers. The comparison of the plate efficiency values determined experimentally with those from different correlations for large columns shows that the equation of MacFarland et al. and the point AIChE theoretical method are the best for predicting mass-transfer efficiency of the small-size bubble-cap Teflon tray used.