Mass transfer coefficients are important in the design of mass transfer equipment such as distillation towers, adsorption and desorption columns, and cooling towers. Increasing the mass transfer coefficient is caused increased efficiency, reduced size and cost of the equipment. This thesis is related to the experimental investigation on using of nanofluid in the gas absorption process in a packed column. To study the proposed title, a glass packed column was design and subsequently fabricated. The inner diameter of column is 30mm, and the height of the column is 90cm. In this work, Fe 3 O 4 / water, SiO 2 / water and NiO/ water were used as solvent in the absorption process. Effect of gas and liquid flow rates and magnetic field intensity on the mass transfer rate and mass transfer coefficients under different nanoparticles concentration were investigated. According to the magnetic properties of Fe 3 O 4 and NiO nanoparticle and polarity of the base fluid molecules, we expected that the magnetic field could have the positive effects on the CO 2 capture process. SiO 2 / water nanofluid with concentration of 0.05, 0.1, 0.2, 0.5, 1 and 1.5 v/v %, Fe 3 O 4 / water and NiO/ water with concentration of 0.002, 0.005, 0.01, 0.05 and 0.1 v/v % have been used. The gas and liquid flow rates in the experiments are 1 and 1.5 lit/min for gas phase and 0.2, 0.26 and 0.32 lit/ min for the liquid phase. The magnetic filed intensity of 240 and 350 G have been used in direct of falling film. The results showed that addition of SiO 2 , Fe 3 O 4 and NiO nanoparticles increase the mass transfer rate and mass transfer coefficients. For SiO 2 / water nanofluid at concentration of 1.5 vol%, the enhancement of mass transfer rate and mass transfer coefficient in comparison with pure water was 36% and 17% respectively. The optimum concentration of Fe 3 O 4 /Water nanofluid is 0.005%, which the enhancement of mass transfer rate and mass transfer coefficient in comparison with pure water was 12% and 10% respectively. The optimum concentration in the NiO/Water nanofluid is 0.01%, which in this point, the enhancement of mass transfer rate and mass transfer coefficient in comparison with pure water was 9% and 6 % respectively. In the optimum concentration of nanofluids, effective mass transfer rate and mass transfer coefficient of Fe 3 O 4 /Water nanofluid were 29.5% and 41.5% higher than those in NiO/Water nanofluid. Under the magnetic field, the maximum enhancement of mass transfer rate in Fe 3 O 4 /Water nanofluid with concentration of 0.005% and in NiO/Water nanofluid with concentration of 0.01%, were 14% and 10.5%, respectively. Performance of Fe 3 O 4 /Water nanofluid for CO 2 capture process under magnetic field was better than NiO/Water nanofluid. Under the magnetic field and in the optimum volume fraction of nanofluids, the effective mass transfer rate of Fe 3 O 4 /Water nanofluid is about 25% higher than NiO/Water nanofluid. For Fe 3 O 4 / water and NiO/ water nanofluids at concentration of 0.1 vol% with magnetic filed of 350 G, the mass transfer rate when the magnetic field is not applied to increase 6.5 and 4%, respectively and the mass transfer coefficient increase 9 and 6, respectively. Key words : packed column, mass transfer, nanofliud, magnetic field