The kinetics of emulsifier-free emulsion polymerization of vinyl acetate using the redox initiation system of potassium persulfate-potassium metabisulfite was studied. The effect of the reaction conditions on the rate of polymerization was also investigated. The polymerization proceeded smoothly until high conversion and yielded stable emulsions. The apparent activation energy for the polymerization system was calculated and the effect of some inorganic substances on the rate of polymerization was also revealed.