Perfluoroacyl amidoximes, RFC (= NOH) NHZ, where RF is CF3, C2F8, CsF,, or CVFIS, were prepared by the addition of hydroxylamine to the corresponding perfluoroalkyl nitrile. Acylation by perfluoroacyl chlorides produced stable 0-perfluoroacyl perfluoroacyl amidoximes, RFC (NH~)= N--OC (= O) RF; these compounds were cyclized by dehydration with phosphorus pentoxide to give 3, 5-bis (perfluoroalkyl)-1, 2, 4-oxadiazoles. Acylation ...