Potassium carbonate is considered a promising solvent for carbon dioxide (CO2) capture as it is cost-effective and environmentally benign when compared to traditional amine-based solvents. In order to increase absorption capacity, the use of concentrated potassium carbonate solvent has been proposed in which CO2 absorption results in precipitation of bicarbonate. Understanding the formation of the solids in that system is important if this is to be used for CO2 capture. In this work, the precipitation behavior in the ternary system of potassium carbonate potassium bicarbonate-water was studied in a batch cooling crystallizer equipped with Focused Beam Reflectance Measurement (FBRM) and an Optimax workstation. The solubility data were validated using a regressed Electrolyte Non-Random Two Liquid (ENRTL) activity model developed in Aspen Plus. The precipitate was determined as kalicinite with hexagonal prism shape by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). using the metastable zone width method and induction time method. Results indicated that in the studied ternary system there were two separate regions corresponding to different nucleation mechanisms, which were defined by the cooling rate. The supersaturation of potassium bicarbonate and the concentration of potassium carbonate determined the nucleation kinetics. On the basis of the calculated nucleation kinetics, the continuous growth mechanism of the crystals was further examined using the surface entropy value and SEM images.