Surface acid-base properties of kaolinite were investigated by potentiometric surface titration. On the basis of the multi-sites model (assuming the presence of (Al-2OH)()(), (AlOH)()() and (SiOH)()()), relative parameters of proton adsorption/desorption were calculated according to the experimental data which had been corrected in consideration of the kaolinite dissolution. The reactions at every site were also discussed. The influence of various ionic strengths and kaolinite dissolution on the results of potentiometric surface titration was studied. The point-of-zero-net-proton charge of kaolinite (pH-(PZNPC),5.2) differed from the point of zero charge. Below pH 5.2, the positive charge at the kaolinite surface was mainly attributed to the formation of silica rich/aluminum deficient precursor complex and proton adsorption at aluminum sites, whereas above pH 5.2, the negative charge at the kaolinite surface was contributed chiefly by deprotonation of Si and Al sites.