This paper uses an ARGET ATRP mathematical modeling to study the solution polymerization of styrene. Differently from previous published works, a detailed parametric study was performed in order to verify how chemical species behave throughout the polymerization process and to provide a numerical tool for analysis, optimization and process scale-up. The key contribution of the present work is to give detailed information about some chemical species, difficult to measure experimentally, under different parametric conditions. Catalyst and reducing agent concentration influence in the polymerization was analyzed. In parallel, catalyst/initiator ratio and catalyst/reducing agent ratio were also studied in order to propose ideal operating conditions. The results showed that catalysts presenting high K-eq values caused the poly-dispersity index to depart from the unit value. Highly active reducing agents can result in its fast consumption limiting polymerization to very low conversions. Moderate quantities of moderately active catalyst and reducing agents show a positive effect in ARGET ATRP, as the final properties of the target polymer and the polymerization behavior remain well controlled throughout the reaction. High quantities of these species, however, proved to induce undesirable effects on the polymerization as the reaction is too fast in the beginning, compromising the reaction extent, polymerization control and the final properties of the polymer. (C) 2016 Elsevier B.V. All rights reserved.124211219