Abstract Comprehensive experimental results are presented for surfactant-free emulsion polymerization of styrene with water-soluble, ionic initiators. Special emphasis is placed on the particle nucleation, the chemical structure of the nucleating species, the change of latex, particle and polymer properties as well as the development of particle morphology with polymerization time. Under special conditions the appearance in transmission electron microscopy pictures of less electron dense anomalous particles is observed. The formation of these structures is discussed and possible formation mechanisms presented. Dialysis of the latexes changed their properties drastically as they became unstable to coagulation. The original latexes did not change their properties over several months.