Poly(vinyl chloride) (PVC) samples were synthesized by a living radical polymerization (LRP) method and compared with commercial PVC prepared by the conventional free radical polymerization (FRP). The differences were assessed, for the first time, in terms of viscosimetry parameters and thermal analysis. The LRP method used to prepare the PVC-LRP samples is the only one available to obtain this polymer free of structural defects, being of commercial interest in a view of preparing a new generation of PVC-based polymer with outstanding performance. The polymerization temperature selected (35 degrees C) to prepare the LRP samples is currently used in the industry to prepare PVC-FRP grades with moderate to high molecular weight. Since the thermal stability is a direct consequence of the polymer structure, this study is of vital importance to understand the potential of new PVC-LRP. The thermoanalytical measurements demonstrate an enhanced thermal stability of PVC-LRP when compared with its FRP counterpart. The PVC-LRP sample with very low molecular weight reveals a higher thermal stability than the most stable PVC-FRP sample. It is the first report dealing with thermal analysis of PVC prepared by LRP. (c) 2008 Wiley Periodicals, Inc.