Reliable estimation of amine degradation, which can lead to significant problems such as solvent losses, byproducts, fouling, foaming, corrosion, and increase in viscosity, is very important for developing effective and efficient amine solvents with high chemical and thermal stability. In this study, thermal degradation of aqueous N,N-diethylethanolamine (DEEA) solution was investigated as a function of temperature, CO2 loading, and DEEA concentration in a 600 mL stainless steel autoclave. The results show that DEEA thermal degradation without CO2 was quite low and was effectively negligible. Also, DEEA solution demonstrated more resistance towards thermal degradation with CO2 than MEA. Furthermore the results of the effects of degradation on the equilibrium solubility of CO2 in aqueous DEEA solution indicates that sonic of the degradation products also have the ability to absorb CO2 resulting in less DEEA make-up to achieve the initial DEEA concentration equilibrium CO2 absorption capacity. A possible mechanism for DEEA thermal degradation has been developed to explain the occurrence of major products generated during the degradation process. In addition, a kinetic model has been established to predict the rate of the thermal degradation of DEEA. The model had an absolute average deviation (PAD) of 3.7% between the experimental rate and the predicted rate. (C) 2015 Elsevier Ltd. All rights reserved.