Acid/basic potentiometric titration can be used to quantify red mud surface charge properties.In this study, the amount of surface active-OH groups and surface charge density on red mud particles generated from Chinese diaspore bauxite were evaluated from acid/basic potentiometric titration data in 0.1 M or 0.5 M NaCl solution.The results show that the adsorption of sodium polyacrylate on red mud surface causes the increase of red mud surface active-OH groups, which is reflected in the shift of the point of zero charge (PZC) to a lower pH value.