The aminolysis of hexachlorocyclodiphosphazane with substituted or unsubstituted arylamines, led to the preparation of some new organophosphorus compounds. It was also possible to isolate some new geometrical isomers containing substituted arylamines. It has been found that the aminolysis reactions of 1,3-diaryl-2,2,2,4,4,4-hexachlorocyclodiphosphazane take place without ring cleavage of the cyclodiphosphazane ring system, leading to 1,3-diaryl-2-oxo-2,2,4-arylcyclodiphosphazanes. The structures of these aminophosphorus compounds were substantiated on the basis of microanalytical data, infrared, ultraviolet and proton NMR spectroscopic evidence. Hexachlorocyclodiphosphazane and some aminosubstituted cyclodiphosphazane compounds were irradiated by gamma-rays and the ultraviolet measurements before and after irradiation were discussed. It was observed that all the absorption bands show the highest absorptivity values at a particular irradiation integral dose for each of the irradiated compounds. From the ultraviolet results and mass spectrometric data, it may be suggested that the possible decomposition sites of the amino-substituted cyclodiphosphazanes are at the double bond between the four-membered ring and the exocyclic phenyl ring and at the double bond between the four-membered ring and the oxygen atom.