Organically modified silica (ormosil) particles were prepared using hydrolytic sol-gel methods and the miniemulsion polymerisation approach. Methyl-, ethyl-, and phenylsilsesquioxane nanoparticles with diameters in the range 50-180 nm were obtained using the modified Stöber method with an aqueous sodium silicate solution used as a seed for further growth of the particles. Methyl- and phenylsilsesquioxane particles were prepared by a sol-gel method in the presence of benzethonium chloride used as a surfactant. The miniemulsion polymerisation approach has been extended to the production of methacrylate-modified silica nanoparticles with vinylpyridine or lauryl methacrylate used as comonomers both in the presence and in the absence of a surfactant. Styryl-modified silica particles with diameters in the range 300-800 nm were obtained by the Stöber method using pre-formed SiO2 nanoparticles as the seeds for silsesquioxane nanoparticle formation. The effect of incorporation of the particles produced using different synthetic methods on hardness and water resistance of acrylic coating systems was studied here.