M. HERNANDEZ-Vr:LEZ, F. FERNANDEZ GUTIERREZ Grupo de zeofitas y propiedades dieldtricas en sdlidos, Facultad de Fisica, Instituto Superior Pedagogico E. J. Varona, C. Libertad. Marianao. C. de la Habana. Cuba The dielectric properties of diamond thin films obtained on silicon substrates by microwave plasma-assisted chemical vapour deposition (MWCVD) have been measured in the frequency range from 0.1 to 103 kHz at different temperatures up to 150 °C. The experimental results have been discussed in terms of the many body theory for dielectric relaxation in solids. Dielectric parameters as well as the d.c. conductivity of the samples have been correlated with the morphology and diamond content in the films, respectively detected from scanning electron microscopy (SEM) and Raman spectroscopy. The calculated activation energies for the dielectric relaxation mechanism agree with those obtained from other measurement techniques used in the electrical characterization of diamond films.