Dielectric spectra of CPVC stabilized with cyanoguanidine were studied in the temperature range 300-450 K and frequency range 10 kHz to 1 MHz. In these conditions, only one clear dielectric relaxation band (alpha-type) associated with dipolar polarization was observed. Dielectric losses was found to directly proportional to the number of dipoles (N) which reflects the orientational distribution of polymer chains in the amorphous region, at which dielectric losses concerned. Calculations of the dielectric modulus AT(T) at low temperature indicate that there is a role of the electrode polarization in the relaxation process. Dielectric loss data were used to calculate the activation enthalpy by two different methods, the obtained value was similar to 450 kJ/mol. (C) 2007 Elsevier B.V. All rights reserved.