Polymerization of styrene initiated by sulphuric acid in methyiene chloride was investigated. The rate of polymerization was proportional to the first pcwer of sulphuric acid concentration, to the first power of monomer concentration at 16°C and to the second power of monomer con¬centration at 0°C. A lineer relation hetween the temperature and limit viscosity numbers of the polymets was derived. The overall activation energy was reported as almost zero kcal in the 16°C to -12.5°C temperature range. The overall rate constant and the rate constants of initiation, propagation and termination reactions were found as 1 .4x10 2L2mol“2s^-, 7, 4x10 5 Lmol_-s“-, 8,lxl0~3 Lmol-Is-1, 4.3xlO-3LmGİ“Is-1 respectively. The rate of polymerization increased as the dielectric constant of the solvent inscreased and a lineer relation is derived between the dielecrric constant of the solvent and the reate of polymerization.