Hypervalent iodine compounds with two I-N bonds, containing 5-substituted tetrazoles as the ligands PhI(N4CR)2 (R = CH3, C6H5, and 4-CH3C6H4), were synthesized from PhI(O2CCF3)2 or PhICl2 and the corresponding tetrazole potassium salts. Alternatively, PhIO was reacted with the free tetrazoles, and the reactions afforded either PhI(N4CR)2 or, in most cases, μ-oxo- or oligomeric compounds with several I and O atoms in the backbone and two terminal tetrazole groups. The isolated compounds were reasonably stable in the solid state as well as in solution at room temperature but explosive at elevated temperatures (135-180 °C depending on the structure). The crystal structure of one representative compound (an oligomer with three I atoms in the backbone and 5-phenyltetrazole end groups) was solved and refined from synchrotron powder X-ray diffraction. The novel compounds were characterized by cyclic voltammetry and were found to be strong oxidants. In addition, they proved to be useful reagents for the iodotetrazolylation of unsaturated compounds such as styrene and cyclohexene and for the transfer of tetrazole groups to N, N-dimethylaniline.