The effect of various NaOH concentration as stabiliser on properties of aqueous SiO₂ sols and their xerogels, prepared in the “polymeric silicic acid (PSA)-water-sodium hydroxide” system, was studied. PSA sol, which was prepared from the solution of sodium silicate by help of acidic ion exchanger, was stabilised by addition of NaOH solution in such a way to preserve the w(SiO₂) : w(Na₂O) weight ratio which was 80:1, 100:1, 150:1, 200:1 and 250:1, respectively. Xerogels were prepared by drying of sols at temperature of 80 °C. The dynamic light scattering method was used for determination of the particle size of stabilised sols. The scanning electron microscopy was applied for observation of the prepared xerogel surfaces. The specific surface area as well as porosity were recognized by help of nitrogen adsorption method. The stable monodisperse sols with diameter particles around 2.0 nm were prepared. In the used range of the concentration of the NaOH stabilizer, the change in concentration has not caused almost any effect on the particle size. The log-normal distribution curves of the size of colloidal particles in the sols were recognized. The stability of the sol was for several months. Based on the image analysis, it was determined that the xerogel surfaces are formed by spherical particles or their aggregates with the mean size approximately 50 nm. The reduction the concentration of the NaOH stabiliser has effect on increase in the specific surface area and xerogels porosity.