Perfluoroazaalkenes R(f)N=CF2 (Rf=CF3, C2F5 C3F7) react with triphenylphosphane to give the respective isocyanides R(f)N=C. This reaction provides a more facile route to the previously described CF3N=C and moreover leads to the new isocyanides C2F5N=C and C3F7N=C. Properties and reactions of C2F5N=C and C3F7N=C with oxidizing agents like Cl-2, Br-2, R(f)OCl (R(f)=CF3, (CF3)(3)C, SF5) and CLF are reported.