Crystallization of a reaction product was observed during the absorption Of CO2 in aqueous potassium taurate solutions at 298 K. The crystallizing solid was found to be the protonated amine. The critical CO2 loading value at which crystallization occurred was measured for various amino acid salt concentrations. A simple relation between the critical CO2 loading value, initial amino acid salt concentration, and solubility of the amino acid in water is established. This relation seems to hold well in predicting the critical CO2 loading value for salts of amino acids other than taurine, for which Hook (Ind. Eng. Chem. Res. 1997, 36, 1779) has recently published some qualitative experimental data. The influence of the formation of the solid reaction product during the absorption Of CO2 in aqueous potassium taurate solutions on the mass-transfer characteristics of a gas-liquid contactor was investigated semiquantitatively for a stirred reactor. In particular, the effect of the presence and absence of crystals in CO2-loaded solutions on the liquid-side volumetric mass-transfer coefficient was studied by carrying out physical N2O absorption experiments in CO2-loaded aqueous potassium taurate solutions.