Two CO2 chemical absorption systems using 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA) aqueous solutions are qualitatively compared in terms of absorption performance and electrical properties. While the absorption capacity is close to their theoretical values in the solutions of concentrations less than 2.0 M AMP and 0.4 M MEA, it decreases below the theoretical values according to the initial concentration (C-ini) in the AMP solutions above 2.0 M, and the primary reaction is changed in the MEA solutions above 0.4 M. Unlike the MEA system, the absorption completion time increases proportionally to C-ini in the AMP system to be about 247.4 min at the 4.0 M solution; however, the variation of the overall absorption rate of CO2 follows a parabolic function of C-ini with a maximum of 17.98 mmol CO2/(L center dot min) in the 0.5 M solution. This difference is primarily due to the instability of AMP carbamate (AMPCOO(-)) caused by the steric hindrance effects and the inhibition of the MEACOO(-) hydrolysis in the two relatively high-concentration solutions. Especially, the amount of generated free-AMP is reduced by the combination of the protonated AMP (AMPH(+)) generated with AMPCOO(-) in the high-concentration solutions. The ionic conductivity of AMPH(+) is 29.1 S center dot cm(2)/(mol center dot z), which is 53.2% less than that of MEAH(+), and the real ionic activity coefficient (RIAC) in the AMP system is always less than that in the MEA system at the same concentration as well as the decreasing ratio of RIAC according to Cini in the AMP system, 0.10 L/mol, was higher than that in the MEA system. The chemical CO2 absorption capacity required to raise the same electrical conductivity in the AMP solution is larger than that in the MEA at the same concentration. These differences between the two systems can be attributed to their different molecular structures and sizes.