Significant differences in the reactivity of isomeric heptafluoronaphthalenes and bromoheptafluoronaphthalenes towards organolithium and organomagnesium compounds were found. Metalation of polyfluorinated naphthalenes 2-C10F7X (X = H, Br) occurs easily under the action of bases (BuLi, t-BuLi, LDA) as well as EtMgBr (X = Br) in ether. This fact was proven by 19F NMR spectroscopy and by trapping of 2-C10F7M (M = Li, MgBr, Mg(2-C10F7)) with electrophile ClSiMe3. The interaction of 1-C10F7Br with BuLi or EtMgBr proceeds in a similar way. In contrast to 2-C10F7H, isomeric 1-C10F7H is the less acidic substrate and undergoes only the nucleophilic alkyldefluorination when combined with BuLi or t-BuLi.