Silicas of highly dispersion degree were obtained using the precipitation technique with sodium metasilicate solution and sulphuric acid. This process includes formation of silica particle and their aggregation. Studies on the surface modification of silicas using silane coupling agents are described. Application of these compounds results in the change of the hydrophilic character to the hydrophobic one. Basic physicochemical analyses of the obtained silica were presented. Moreover, studies on morphology and microstructure using scanning electron microscopy (SEM) were performed. The zeta potential, polydispersity and changes in the tendency to form agglomerates and aggregates of the particles were also described. Silicas modified with any of the examined silanes manifest a decreased tendency to secondary agglomerate formation and in many cases uniform silicas were obtained.