A laser holographic interferometer with optical magnification was designed and used in this work for the study of concentration fields near the interface and mass transfer phenomena of a gas bubble moving against a countercurrent liquid stream. The concentration profiles in liquid phase near the frontal and rear interfaces of a bubble were measured quantitatively for the systems containing carbon dioxide as gas phase and methanol

ethanal and n-propanal as liquid phase respectively. It was found that the liquid phase concentration at a close distance to the interface in the order of 10-2mm

designated as quasi-interface concentration

was far from the thermo-dynamic equilibrium value. The concentration fields near the frontal and rear interfaces differed considerably

and such differences were affected by both the liquid phase velocity and equivalent diameter of the bubble. Inner circulation within a bubble was viewed from the hologram in the bubble formation stage

and it disappeared soon afterwards. Experimental results were discussed from the basic mass transfer equation by means of scale analysis.