O-Vinylamidoximes 2 are synthesized from amidoximes 1 and acetylene in superbase systems (KOH/DMSO, KOH/NMP, NaOH/CsF/NMP) in a preparative yield of up to 80%. They decompose explosively above 150 °C, being resistant to solvolysis in the KOH/DMSO system (100 °C, 3 h) and to polymerization (AIBN, UV). Trifluoroacetylation of O-vinylbenzamidoxime 2b with (CF3CO)2O/pyridine gives 5-trifluoromethyl-3-phenyl-1,2,4-oxadiazole (3) in 49% yield.