Carbon dioxide (CO2) absorption into highly concentrated solutions of monoethanolamine (MEA) was studied. The effect of operating parameters on the overall mass transfer coefficient (KGav) was determined in a pilot-plant scale absorption unit. The (KGav) increased at low solution concentrations, decreased at intermediate concentrations, and increased as the concentration became high (54 wt%). The (KGav) increased with an increasing liquid flow rate, decreased with an increase in either the CO2 loading or the CO2 partial pressure, and was not affected by the inert gas flow rate. Finally, structured 4A Gempak packing produced (KGav) values twice as high as randomly packed IMTP#15 or 16-mm Pall Ring systems.