Studies were undertaken on the precipitation of highly dispersed magnesium silicate. Solutions of sodium metasilicate and of magnesium salts [chloride, sulfate(VI) or nitrate(V)] were employed. The chemical reaction of silicate precipitation was corrected by supplementation of the system with diluted (5-15 wt%) solutions of sodium hydroxide. Optimum parameters of the precipitation process were established. The precipitated magnesium silicates were comprehensively examined. Their chemical composition and principal physicochemical properties were established, including bulk density, capacities to absorb water, dibutyl phthalate and paraffin oil as well as the sedimentation rate in linseed oil. Moreover, their morphology, microstructure and particle size distribution were studied, using scanning electron microscopy and dynamic light scattering technique. The obtained products manifested variable physicochemical properties. The presence of sodium hydroxide solution in the course of precipitation proved to significantly affect the quality of the obtained magnesium silicates.