Carbon dioxide is considered as the main greenhouse gas responsible for climate change. Absorption of CO2 by liquid phase has gained attention as a means of mitigating environmental challenges. In this study, the effect of Fe3O4 nanoparticles on the CO2-water mass transfer coefficient was experimentally evaluated in the presence and absence of a magnetic field. The absorption experiments were carried out in a falling liquid film absorber system in laminar and turbulent flow regimes. Fe3O4/water nanofluid was used in 0.001-0.05 vol% concentrations. The results show that adding Fe3O4 nanoparticles to water increases the mass transfer coefficient (MTC), and that it increases with an increase in nanofluid concentration. For a concentration of 0.05 vol% nanofluid, the MTC was improved 111% and 13.7% in the turbulent and laminar flow regimes, respectively. The mass transfer coefficient of CO2 in water and effective mass transfer coefficient in nanofluid were increased up to 10% and 29% in the presence of a parallel alternative magnetic field, respectively.