The reaction kinetics or the absorption of CO2 into mixed aqueous solutions of piperazine (PZ) and triethanolamine (TEA) are investigated using the wetted wall column at temperatures or 303.2 to 313.2 K. The physical properties such as density and viscosity of the aqueous alkanolamine solutions, and the solubility and diffusivity of the nitrous oxide in aqueous alkanolamine solutions are also measured. The N2O analogy is applied to estimate the solubilities and diffusivities or CO2 in aqueous amine systems. Based on the pseudo-first-order for CO2 absorption, the overall pseudo first-order reaction rate constants were determined from the kinetics measurements. For CO2 absorption into mixed aqueous solutions or PZ and TEA, it is found that the addition or small amounts of PZ to aqueous TEA solutions has a significant effect on the enhancement of the CO2 absorption rate. For the CO2 absorption rate model, a second-order reaction rate model is applied for both reactions of CO, with PZ and TEA. The overall absolute percentage deviation for the calculation of the apparent rate constant k(app) was 4.6% for the kinetics data measured. The model is satisfactory in representing the CO2 absorption into mixed aqueous solutions of PZ and TEA.