An experimental and theoretical investigation of the absorption of carbon dioxide into aqueous blends of monoethanolamine and N-methyldiethanolamine has been conducted. A mathematical model which is capable of predicting gas absorption rates and enhancement factors from chemical reaction kinetics, system hydrodynamics, and physical properties was developed. The CO2 absorption was modeled as a system of parallel reversible reactions according to Higbie’s penetration theory. The model was also used to estimate the rate coefficient of the reaction between CO2 and monoethanolamine at 313 K from experimentally measured absorption rates.