The influence of the amino acid D,L-methionine on the solubility of carbon dioxide in pure water and in aqueous solutions of potassium carbonate was investigated. The solubility was measured with a high-pressure view-cell technique operating on the synthetic method. Temperature and total pressure ranged from about 353 to 393 K and 1 to 10 MPa, respectively. The molality of methionine was between about 0.42 mol.(kg H2O)(-1) and 0.83 mol.(kg H2O)(-1). The molality of potassium carbonate was about 1.25 and 2.5 mol.(H2O)(-1). The solubility of carbon dioxide in aqueous solutions of potassium carbonate and methionine is influenced by chemical reactions: On one side, dissolving carbon dioxide in an aqueous solution of potassium carbonate shifts the chemical reaction equilibrium from carbonate to bicarbonate and, on the other side, methionine is a zwitterionic substance. The new experimental results are correlated using an extension of a previously published thermodynamic model for the solubility of carbon dioxide in aqueous solutions of potassium carbonate.