We study the processes involved in metallocene activation and further propylene polymerization. In this paper, we begin by analyzing the behavior of soluble metallocene in propylene polymerization before advancing to the study of the heterogeneous polymerization. Experimental data obtained in a semibatch laboratory polymerization reactor using ethylenbisindenylzirconium dichloride (EtInd(2)ZrCl(2))/methylaluminoxane (MAO) are combined with a mathematical model providing useful information such as number of active sites and their activation patterns. We present a mathematical model for the reactor that predicts not only reactor productivity but also the molecular properties of the product. We apply the model to soluble systems in order to find the optimal parameters for the catalyst itself and in the presence of different types of additives such as aluminum chloride (AlCl3) and ethyl benzoate (E.B.).