In this work, we present a detailed structural analysis of poly(4-chloromethystyrene) (P(4-CMS)) by 1D and 2D NMR methods A signal assignment and quantitative analysis of the different all phatic structures of the polymer backbone were achieved. Combining signal integration of spectra taken in both C6D6 and CD2Cl2 as solvent, the content of terminal (T), vinyl-type linear (L-v). condensation-type linear (L-C), and dendritic (D) units and thus the degree of branching could be determined. The study is completed by it kinetics study of the polymerization of 4-CMS at 115 degrees C in chlorobenzene with CuCl/bpy its activator. The development Of subunits is followed depending oil vinyl group conversion and compared with it theoretical study of Muller et al. Obviously, the fractions of structural units cannot be predicted by a simple theoretical model due to the complexity or the mechanism of the atom transfer radical polymerization (ATRP) An increased content of L-v units is rationalized by both a retarded deactivation resulting in multiple monomer addition steps and a higher reactivity of the secondary radical compared with the primary one.