The polymerization of vinyl acetate at 60 degreesC in microemulsions stabilized with the anionic surfactant, Aerosol OT, with or without cosurfactant (n-butanol) is examined. Partial phase diagrams at 60 degreesC show that the addition of n-butanol enhances the one-phase microemulsion region. Results indicate that the reaction rate is not affected by the presence of the alcohol. However, average molar masses are smaller although particles are bigger throughout the reaction compared to those values obtained in the absence of n-butanol. An explanation for these results is presented. (C) 2003 Elsevier Science Ltd. All rights reserved.