Abstract Quantitative 13C NMR spectroscopy was used to study the reaction of CO2 with aqueous amines. A number of structurally different amines were studied using this method to investigate their CO2 absorption and desorption under different reaction conditions. The results demonstrate that this method is easily applicable to both CO2 absorption and desorption with aqueous amines solutions. The study showed that this technique can be used to investigate the reaction mechanism of amine solvents with CO2, and also give their absorption and desorption capacities. The easy application of this method to monitor speciation of the amine- H2O–CO2 reaction system makes it a useful tool in the development of new amine solvents for post combustion capture (PCC).