This work presents experimental data for the CO₂ solubility in aqueous blends of diethanolamine (DEA) + 2-amino-2-methyl-1-propanol (AMP) and diethanolamine (DEA) + N-methyldiethanolamine (MDEA) at temperatures of (303.1, 313.1, and 323.1) K and CO₂ pressure in the range of (1 to 350) kPa. Aqueous ternary mixtures of (DEA + AMP) and (DEA + MDEA) with the following compositions (0.06 mass fraction/0.571 mol·L^–1 DEA + 0.24 mass fraction/2.692 mol·L^–1 AMP), (0.09 mass fraction/0.856 mol·L^–1 DEA + 0.21 mass fraction/2.356 mol·L^–1 AMP), (0.12 mass fraction/1.141 mol·L^–1 DEA + 0.18 mass fraction/2.019 mol·L^–1 AMP), and (0.15 mass fraction/1.427 mol·L^–1 DEA + 0.15 mass fraction/1.683 mol·L^–1 AMP) and (0.06 mass fraction/0.571 mol·L^–1 DEA + 0.24 mass fraction/2.014 mol·L^–1 MDEA), (0.09 mass fraction/0.856 mol·L^–1 DEA + 0.21 mass fraction/1.762 mol·L^–1 MDEA), (0.12 mass fraction/1.141 mol·L^–1 DEA + 0.18 mass fraction/1.511 mol·L^–1 MDEA), and (0.15 mass fraction/1.427 mol·L^–1 DEA + 0.15 mass fraction/1.259 mol·L^–1 MDEA) were considered. The total alkanolamine mass fraction was held constant at 0.3. The solubility data produced were correlated within a thermodynamic framework using an extended Debye–Hückel theory of electrolytic solution and the virial equation of state.