AbstractThe dielectric behaviour of liquid cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and cyclodecanone in the radio frequency band 1 … 250 Mcps at temperatures between 15° and 45° C has been investigated. The real part of the dielectric constant was found to be independent of frequency. From loss measurements the Cole parameter was found to be zero and the relaxation time to be noticeable higher for cyclooctanone than for the other ketones.