The patent describes a process for producing highly uniform microspheres of silica with an average diameter ranging from 0.1 to 10 μm. The process involves the use of a two-phase liquid mixture of precursor solutions, which initially yield a two-phase reaction mixture. The precursor solutions typically consist of a hydrolyzable silica precursor (such as tetraalkoxysilanes), an alcohol, ammonia, and water, with specific proportions to form the two phases. The process can be initiated in the absence of seed particles or with preformed microspheres. The two-phase mixture becomes single-phase as the reaction proceeds, and the microspheres can be grown to the desired size in the single-phase medium. The invention allows for the control of the physical properties of the spheres, including their porosity and surface area. Examples demonstrate the effectiveness of the process in producing uniform microspheres with controlled characteristics.The patent describes a process for producing highly uniform microspheres of silica with an average diameter ranging from 0.1 to 10 μm. The process involves the use of a two-phase liquid mixture of precursor solutions, which initially yield a two-phase reaction mixture. The precursor solutions typically consist of a hydrolyzable silica precursor (such as tetraalkoxysilanes), an alcohol, ammonia, and water, with specific proportions to form the two phases. The process can be initiated in the absence of seed particles or with preformed microspheres. The two-phase mixture becomes single-phase as the reaction proceeds, and the microspheres can be grown to the desired size in the single-phase medium. The invention allows for the control of the physical properties of the spheres, including their porosity and surface area. Examples demonstrate the effectiveness of the process in producing uniform microspheres with controlled characteristics.