Direct fluorination of uracil, cytosine and their derivatives, in the presence of a non-aqueous solvent, by fluorine gas to produce 5-fluorouracil, 5-fluorocytosine, 5-fluorouracil derivatives and 5-fluorocytosine derivatives is disclosed. The non-aqueous solvent is an acid or alcohol, which can be partly or fully fluorinated or chlorinated, of up to 8 carbon atoms, such as trifluoroacetic acid. Novel compounds produced by the reaction, such as 5,5-difluoro-5,6-dihydro-6-(2,2,2-trifluoroethoxy) uracil are also disclosed. The derivatives and 5-fluorocytosine are useful as germicidal and antineoplastic agents while 5-fluorouracil itself is a known cancer chemotherapy agent.