The hydrolysis and polycondensation of tetraethoxysilane are studied at low pH values in the presence of doping additives (cations of various metals). The period of gel formation is found via viscometry, and the activation energy is calculated. It is shown that the doping additives affect both of these parameters. A change in particle size during the hydrolytic polycondensation of tetraethoxysilane in the presence of metal cations is studied via dynamic light scattering. The structural characteristics of the gels-the radius of gyration and the fractal dimension of the surface-are found through small-angle X-ray scattering. A mechanism of particle formation-kinetically controllable aggregation of a cluster-cluster type-is proposed.