Polycondensation of methyltrimethoxysilane in the presence of the surfactant benzethonium chloride yields strictly spherical organosilicon micronetworks of controlled size in the range of 3 nm less than or equal to R less than or equal to 15 nm with R the particle radius. After a short induction period the size of the particle increases linearly with the cube root of added monomer volume which proves the number of growing nuclei to be constant with time or conversion, whereas the mechanism controlling the number of growing nuclei remains unclear. In many respects the polycondensation resembles a condensation in mu-emulsion although the surface are per surfactant molecule (headgroup area) is shown to decrease with decreasing particle size, a fact which is not yet understood. The particle density in solution is only about one-third of the dry particle density which means that the mu-network is considerably swollen in solution.