Waterborne polymer inorganic hybrids have the potential of both surpassing the performance and targeting applications that are out of reach of conventional polymer dispersions. The properties of these hybrids are determined by the particle morphology achieved during the synthesis. In this work, the evolution of the particle morphology during the polymerization of (meth)acrylate monomers in the presence of CeO2 was determined by cryo-TEM. Moreover, a mathematical model for the dynamics of the particle morphology during the synthesis of polymer inorganic hybrids was developed, and its capabilities were checked against the experimental data. It is our hope that this study will help to further elucidate the mechanism involved in the process and to lay the foundations for a fine control of particle morphology of these materials.