In view of global warming, improvement of CO2 capture efficiency in addition to carbon valorization has become a major concern. In the last decade, post-combustion capture using amines evolved as one of the most mature technologies for industrial applications. The understanding of mass transfer phenomena is still a challenge for enhancing the absorption step. The mass transfer in a spray column during CO2 absorption using monoethanolamine as a solvent was characterized. An innovative optical technique called global rainbow technology as a non-intrusive approach to investigate mass transfer is used to measure the amount of CO2 absorbed in a cloud of droplets in the spray. The CO2 absorbed flux obtained from experiments is compared to a basic mass transfer model simulated on Comsol Multyphysics (R).