Secondary amines have been proposed as potential solvents for CO2 capture. In this study, the CO2 solubility of three secondary alkanolamine aqueous solutions, 2-(butylamino)ethanol (BAE), 2-(isopropylamino)ethanol (IPAE), and 2-(ethylamino)ethanol (EAE), were measured with a pressure range of 0.02 to 395 kPa at 40, 80, and 120 degrees C. A static method based on an equilibrium cell unit was used for measurements in high CO2 equilibrium partial pressure regions at over 1 kPa, while the flow method based on a modified gas sparging reactor unit proposed by Kim et al.(2017) was employed for measurements in low pressure regions under 1 kPa. Two amine concentrations, 15 and 30 wt %, were considered for each amine, and their CO2 solubility was represented by the Kent-Eisenberg model. The cyclic CO2 absorption capacity and heat of the reaction for the three secondary alkanolamines were compared with those of monoethanolamine (MEA).