The dielectric properties of oxyviscose samples prepared with different oxidizing agents were investigated. The results obtained are interpreted and compared from the viewpoint of the modifications that occur in the structure of the fibres during the oxidation processes. These modifications were determined by infra-red spectroscopy, X-ray diffraction, degree of polymerization, copper number, total carbonyl content and carboxyl content. The relative permittivity and loss index were measured over a frequency range from 0.1 to 100 kHz and temperature range from -50 to 100 degrees C. The dipolar group involved in the secondary relaxation processes was concluded to be the methylol group in the non-crystalline regions.