Determination of fluoride at trace level is important for the specification analysis of nuclear fuel samples. This is generally accomplished by pyrohydrolytic separation followed by ion selective electrode potentiometry. In the present work, a method has been developed for the determination of fluoride by radiometric assay of181Hf back-extracted from thenoyltrifluoracetone (HTTA) in benzene.181Hf back-extracted is proportional to the concentration of fluoride.