The present paper deals with the surface charge properties and dispersion stability of aqueous silica suspension. The zeta potential was measured versus barium acetate and zinc acetate concentration, at pH 6.0. EDTA was used to chelate the bivalent metal ions, so that the charge of counterion was reduced. The complexation of bivalent counterions favors the increase of the negative zeta potential and the dispersion stability of aqueous silica suspension. (C) 2003 Elsevier B.V. All rights reserved.