The formation of bicarbonate ions in an amine solution during CO2 absorption results in lowering the heat duty for amine solvent regeneration in the CO2 capture process because bicarbonate breakdown needs the lowest energy input to release CO2. In this study, bicarbonate formation was conducted for two mixed solvents consisting of tertiary amines (1DMA2P (1 M) or MDEA (1 M)) blended with MEA in order to determine both formation rate and capacity of bicarbonate ions as compared to MEA alone. The amines and concentrations used in the study were MEA (5 M), MEA MDEA (5:1 molar ratio, 6 M total), and MEA-1DMA2P (5:1 molar ratio, 6 M total) at various CO2 loadings. The formation of bicarbonate ions was evaluated using C-13 NMR technique at 293.15 K. The results show that for the single tertiary amine system higher concentrations of bicarbonate ions were formed for MDEA than for 1DMA2P for the same CO2 loading. The results for the blended amine systems showed that bicarbonate ions were generated at CO2 loadings lower with MEA alone than with MEA-1DMA2P generating bicarbonate ions at a CO2 loading (0.34 mol CO2/mol amine) lower than that with MEA MDEA (0.38 mol CO2/mol amine). Thus, as an additive in MEA, 1DMA2P has a better potential than does MDEA to generate bicarbonate ions at a leaner CO2 loading with the attendant lowering of the regeneration energy.