This project was performed to study the effect of initiator addition method on the suspension polymerization of vinyl chloride monomer (VCM) in order to increasing the productivity of suspension poly (vinyl chloride) (S-PVC) in batch-wise reactors. A set up contains reactor and other equipments was designed for these experiments. After reactor evaluation, required experiments were performed. Initial experiments were performed for the production of S-PVC based on grade S-70 with MYPC initiator according to Bandar Imam Petrochemical Company and guidelines recipe were obtained. Several experiments were conducted to investigate the effect of continuous dosage of a fast initiator (Trigonox 187) on the polymerization reaction kinetics and product properties. With continuous dosage of fast Trigonox 187 initiator, PVC suspension polymerization time and initiator consumption are decreased as 54% and 16% respectively at same conversion. The porosity of the samples which specified by cold plasticizer absorption is increased by 35%, that SEM micrographs confirm this high porosity. With increasing porosity, bulk density of PVC powder is decreased about 3%, but there is in the range of standard properties. Particle size analysis of PVC powder shows that with continuous dosage of fast initiator, mean particle size is increase and particle size distribution is a little broader. K value as a molecular weight characteristic of PVC is slightly decreased. Also, due to high porosity of PVC powder and low half-life of the initiator, unreacted monomer and volatile residues in the product are very low. Other experiments have been carried out as well as to the importance of the dosage method and half-life of the initiator and was shown that when all of the fast initiator is added to the reactor at binging of the process, the reaction was terminated at short duration and low conversion is obtained. Continuous dosage of slow Trigonox EHP initiator not only did not decrease the process time, even the process time is also increased. These results showed that, continuous dosage method should be done by the use of a fast initiator with very low half-life at process temperature. Chemical analysis showed that the total number of branches, internal bonds and labile chlorine atoms per 1000 monomer units in the chain is lower for PVC samples prepared in initiator continuous dosage conditions. It was found that the thermal stability as characterized by dehydrochlorination rate and TGA improved for PVC produced by initiator continuous dosage. The evolution of these structural defects was obtained with conversion. The Brabender plastograph and DSC data indicated that the final PVC synthesized with initiator continuous dosage trajectory showed lower fusion time and higher thermal stability time and degree of fusion. Also, a series of polymerization experiments were performed to evaluate the effect of pre-dissolving the initiator in the VCM monomer before the addition of the continuous phase. Particle size analysis, product characterization and SEM images provided from PVC powder are demonstrate, that by pre-dissolving the initiator in the monomer, particle size distribution is narrower, average particle size is larger and the outer surface of the particles are smother, conversion is increased, porosity or internal pores of the particles and bulk density are declined, but the K value or average molecular weight is remained almost unchanged. By pre-dispersing suspending agents in the monomer along with initiator, the porosity of the product is improved but conversion and the particle size are reducing and particle size distribution is wider. It should be noted that along the experiments in the reactor, a mathematical modeling for kinetic of PVC suspension polymerization reaction with continuous dosage of initiator was provide and then evaluated and verified by using experimental data. This model is used to predict the rate of initiator dosage and other process parameters. Eventually, all of the experimental results were compared with the model data and model accuracy was confirmed. Keywords: Poly (vinyl chloride), Suspension polymerization, Continuous dosage, Reaction rate, Modeling, Morphology, Molecular characteristics, Thermal stability.