Effect of surface ion-exchange of Georgia kaolin on the dispersion characteristics and the rheological properties were studied. The ion-exchange was carried out individually with mono-valent cations (Li⁺, Na⁺, K⁺), divalent cations (Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Co²⁺), and tri-valent cations (Al³⁺, Fe³⁺), using corresponding chloride solution. The zeta potential increased positively from -30 to +7mV by the ion-exchange in the order of mono-<di-<tri-valent cations and simultaneously the viscosity of the slip increased, while the pH decreased from 6.2 to 3.7. Therefore, the zeta potential was considered to be strongly affected by the pH of slurry, but not by absorbed cations on the kaolinite particle. The water film thickness was evaluated by both the measurement of weight loss from 40 to 100°C for the green body and the DSC measurement. A positively linear relationship was observed on the values between the former and the later measurement, excluding trivalent cations, though the later values are about four-times higher than the former values. The water film thickness was increased by the ion-exchange with di-valent cations rather than mono-valent cations. The water film thickness is found to be related with the hydration energy of ion-exchangeable cations.