BACKGROUND Carbon capture and storage is considered one of the pillars that should support greenhouse gas (GHG) emission mitigation by 2050. In this sense, partial oxy-combustion emerges as a promising alternative. Its advantages rely on the production of a higher CO2 concentration flue gas than these provided by conventional air-firing processes. The use of higher CO2 concentrations should improve the solvent kinetic and the CO2 cyclic capacity. RESULTS The kinetic behaviour of two representative sterically hindered amines, namely 2-amino-2-methyl-1-propanol (AMP) and isophrondiamine (IF), were studied under partial oxy-combustion conditions in a laboratory-scale semi-batch reactor. The CO2 concentration varied from 15%v/v to 60%v/v. The kinetic enhancement experienced by AMP at high CO2 concentration was slightly >60%, instead of 70-80% for IF. AMP also improved its CO2 absorption capacity by 24.7%, from 15%v/v to 60%v/v, almost doubled the improvements achieved by monoethanolamine (MEA). In the case of IF experiments, the CO2 loading increased approximate to 10% from 15%v/v to 60%v/v CO2 and it changed from 1.10 to 1.34 mol CO2 mol(-1) solvent, representing a >20% increase. CONCLUSIONS The presence of higher CO2 concentrations accelerated CO2 absorption and provided higher CO2 absorption rates. In addition, the evolution of the CO2 loading also exhibited higher values in the experiments using higher CO2 concentration flue gas. The steric hindrance causes a hybrid behaviour in these solvents, between both fast and slow kinetic solvents. The kinetic rates observed using AMP were slightly higher than MEA, but lower than IF which showed the fastest kinetics. (c) 2020 Society of Chemical Industry