A process for producing spherical polymer particles which may be either monodisperse of a predetermined and controlled size, or polydisperse, using a liquid atomization technique. The process includes an aerosol generator to create a stream or multiple streams of liquid droplets sprayed into a thermal reactor. The aerosol generator sprays the feed solution which comprises liquid organic monomers or semi-polymerized monomers, a polymerization catalyst and optionally, a solvent, into the thermal reactor environment. The solvent evaporates allowing polymerization reactions to commence. Polymerization may proceed by a variety of methods. Polymerization is completed during the flight-time of the droplets and the solid polymer particles are collected at the bottom of the reactor. The size of the particles in every batch may be predetermined and controlled by fine tuning the aerosol generator's configuration or operational parameters to adjust the size of the droplets of the feed solution being sprayed into the reactor. In one variation, the feed solution to the aerosol generator may be a polymer dissolved in an appropriate solvent. The aerosol generator then sprays the polymer solution in the thermal reactor to generate particles by evaporating the solvent
