Dispersion properties of colloidal silica were studied at subsequent stages of silica sols preparation. Dilute sols were obtained from solutions of sodium silicate by ion exchange method. In them SiO₂ particles were built up and next the sols were concentrated. The concentrations of the sols in which SiO₂ particles were built-up ranged from 5.89 to 6.44 wt. % SiO2, while the mean concentrations of the sols which were added into the heel sols were 3.28 and 6.20 wt. % SiO₂. The particle size distributions were measured by DLS, while the contribution of the ionic form of silica was determined by the colorimetric method on the basis of the intensity of the yellow colour coming from the heteropolycomplexes of silicomolybdic acid.