A series of novel hexasubstituted cyclophosphazene hydrazones [N3P3(single bondOC6H4single bondpsingle bondCHdouble bond; length as m-dashNsingle bondNHsingle bondC(O)single bondC6H4single bondpsingle bondX)6] (X = H, Br, Cl, F, OH, OCH3, CH3, NO2, NH2) were prepared by a sixfold condensation reaction of [N3P3(single bondOC6H4single bondpsingle bondCHO)6] with para-substituted benzoic hydrazides [NH2single bondNHsingle bondC(O)single bondC6H4single bondpsingle bondX] with excellent yields (91–98%). The structures of the compounds were confirmed by elemental analysis, FT-IR, 1H, 13C, 31P, 2D-HSQC NMR and mass spectrometry (MALDI-TOF). All the synthesized cyclophosphazene hydrazones exhibit high thermal stability. The crystal structure of a homogeneously substituted hexakis(4-formylphenoxy)-cyclotriphosphazene was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic system, space group P21/n with a = 16.558(3) Å, b = 10.250(2) Å, c = 23.429(5) Å, α = γ = 90.00°, β = 90.461(4)°, V = 3976.5(14) Å3 and Z = 4. The R value is 0.0823 for 4290 observed reflections. The conformations of the 4-formylphenoxy-groups are different at the three phosphorus atoms.