This work presents a study of preparation and characterization of electric and dielectric properties of diatomite-titania and diatomite-niobia mixtures. The sintering temperature and dilatometric curves of the samples were measured, along with their dielectric properties: capacitance, dielectric constant and quality factor. The results suggest that diatomite, when combined with dielectric ceramics, may be considered a technological and economically viable option as dielectric material in the manufacture of ceramic disc capacitors.