ATRP is one of the most successful techniques to control the radical polymerization (CRP) of a great variety of monomers. ATRP allows control of molecular mass, molecular mass distribution and functionality in the polymerization of styrenes and enables synthesizing new polymeric materials having specific properties. Although ATRP is a well established technique, its industrial application requires more insight into the kinetics and thermodynamics of the reactions involved in the polymerization process.