The effect of polymerization time, temperature, monomer concent¬ration on, the rate of polymerization and molecular weight of the poly¬mers prepared from oc-methyl styrene using sulphuric acid catalyst had been previously investigated (Şanlı, Pulat, 1981). It was observed that the molecular weight of the polymers ıncreased as the temperature decreased. On the othcr hand, the rate of polymerization increased to a certain temperature then decreased. Change in the polymerization time did not affect the molecular weight of the polymers obtained. It was also reported that as the monomer and catalyst concentration inc¬reased the rate of polymerization also increased. a-methyl styrene was polymerized using different amounts of water as cocatalyst. As the water concentration was increased the rate of polymerization, and the molecular weight of the polymers were decreased