In this work, 3-Dimethylaminopropylamine (DMAPA), 3-Diethylaminopropylamine (DEAPA) and 3-Piperidinopropylamine (3PDPA) were selected to investigate the influence of substituent type to the CO2 capture performance. The molecular structure of selected diamines can be described as H2NCH2CH2CH2N-R-2 (R = CH3, CH2CH3 and -(CH2)(5)-). The experimental results shows that the -CH2CH3 as a substituent connected to N-atom is better than -CH3 and -(CH2)(5)- for the higher CO2 equilibrium solubility, more bicarbonate formation, lower heat of CO2 absorption, higher CO2 cyclic capacity, faster CO2 initial release rate and higher CO2 removal efficiency. In addition, the mass transfer performance of DEAPA and DMAPA also are investigated by using a wetted wall column and the results displays that both of them shows better mass transfer performance compared to MEA and MEA-DMEA, MEA-DEEA and MEA-AMP and it further reveal that the -CH2CH3 is better than -CH3 as a substituent on N-atom for CO2 transfer. DEAPA has a lower heat of absorption and higher CO2 solubility than most conventional amines and that suggests DEAPA has a potential to be an alternative solvent for the CO2 capture. Therefore, it can conclude that the -CH2CH3 has more advantages than -CH3 and -(CH2)(5)- as a substituent at N-atom for designing an efficient CO2 capture solvent. (C) 2017 Elsevier Ltd. All rights reserved.