During emulsion polymerization of vinyl acetate (VAc) specific interactions surfactant-monomer and surfactant-initiator has been evidenced. Due to this interactions the cmc of the surfactant is higher and the electrical conductivity sharply decreases at surfactant /initiator molar ratio = 1. At this ratio high chemical interaction between surfactant and initiator-has been observed. The surfactant was dissodium salt of the sulfosuccinic acid with nonyl phenol ethoxylated having 25 moles ethylene oxide (NPED25SS) and the initiator was potassium persulfate (KPS). The surfactant-monomer interaction reduces the concentration of free surfactant and consequently the rate of initiator decomposition. For the polymerization reaction, the initiator productivity is higher at lower surfactant concentration. fit a surfactant/initiator molar ratio = 1 this productivity is smaller at constant surfactant concentration.