The accuracy of measuring thermal energy of carbon dioxide removal was confirmed to be improved by using an advanced bench-scale CO2 recovery equipment (gas throughput 6 m(3)/h). The energy for regeneration of spent liquor was evaluated to be 4.8 x 10(3) kJ/kgCO(2) in the case of monoethanolamine as an absorbent. This value is found to compare to that encountered in a pilot plant (gas throughput 600 m(3)/h), whose value has been found to be 3.9x10(3) kJ/kgCO(2). Such a bench-scale test can reduce the liquid quantity to 1/50 of that used in a pilot plant.