In this study a novel strategy for increasing and also controlling mass transfer rate in gas-liquid system is reported and used to the industrially important system of CO 2 absorption. The strategy makes use of Fe 3 O 4 nanoparticles in the liquid phase and also exerting external electric field. To demonstrate this approach, a unique experimental set up has been applied to form falling liquid film, which is water, to be in contact with gas phase, which is pure carbon dioxide. Experimental set up consisted of vertical capillary tubes in four different diameters of 6, 8, 10, 14 mm and two copper electrodes for exerting electric field. Capillary tubes were placed between two electrodes and filled by liquid while gas was injected in the liquid phase by means of a syringe. After injection, gas phase in the form of a bubble was rising up through the tube and liquid falling film created on the boundary of the gas bubble and absorption process happened. Length of bubble reduced due to the absorption process. Length variation of bubble was recorded by taking photos at the entrance and exit sections of the tube and mass transfer coefficient was calculated. Gas bubble was being exerted to the electric field by rising up and passing through the electrodes. Nanofluid was purchased in stable concentrated suspension and diluted to the specific concentration by addition of distillated water. The diluted suspension was stable and no sign of sedimentation was observed in stagnant nanofluid. Nanofluids with concentrations of 0.001%, 0.005%, 0.01%, 0.025% by volume and field intensities of 133, 200, 266 kV/m were used in this study, respectively. Experimental results showed that external electric field is able to remarkably enhance gas absorption rate in the based liquid, while deteriorates mass transfer in nanofluids. The maximum amount of enhancement in mass transfer coefficient was measured to be about 45% and the maximum amount of reduction in mass transfer coefficient was about 63.5% in nanofluid with 0.005% concentration, both at the highest field intensity used in this work (266kV/m). The ratio of mass transfer coefficient under electric field to that in the absence of field versus Reynolds number reached a peak at 1.45 in base fluid whereas a minimum at 0.4 was observed in 0.001% concentration nanofluid. The diffusion coefficient and viscosity of base fluid and nanofluid were also measured under electric field experimentally. It was observed that viscosity of nanofluid increased under electric field. This effect is due to the chain formation of particles in the suspension induced by their polarization. Increasing viscosity leads to increasing resistance for transferring absorbed component from interface to the bulk of liquid, decreasing flow rate, increasing falling film thickness and then decreasing mass transfer coefficient. Also it was observed that exerting electric field decreased diffusion coefficient in nanofluid. Decreasing diffusion coefficient leads to decreasing mass flux in the direction perpendicular to the falling liquid film. Measured mass transfer and diffusion coefficients were compared with film and penetration theories. Experimental data was in agreement with penetration theory. Key Words : mass transfer, nanofluid, electric field, absorption.