The polymerization kinetics of PMMA-seeded styrene emulsion polymerization was studied. Batch polymerization technique was employed and gravimetric method (Total Solid Content) was utilized to determine the monomer conversion. The monodispersed PMMA latexes were used as seed latexes. The rate of polymerization per particle was found to be increased with K₂S₂O₈ concentration and linearly proportional to the diameter of PMMA seed latexes. The dependence on the diameter become more pronounced at higher temperature range. However. the rate was decreased with the addition of chum transfer agent (CHBr₃) because of the easy desorption of the transferred radicals. The activation energy of polymerization was 53.2 KJ/mole and the propagation rate constant was 3301 1/(mole-sec).