The reactions of p-FC6H4OSiMe3 with N3P3F4X [where X is either 1,2-O2C6H4 or 2,3-O2C10H6] provide a convenient route to fully substituted phosphazenes, N3P3(p-FC6H4O)4X. The X-ray structures of the monospiro phosphazene derivatives of 1,2-benzenediol [4,4,6,6-tetrakis(4-fluorophenoxy)-2,2-(1,2-phenylenedioxy)-1,3,5,2,4,6- cyclophosphazene, (1), C30H20F4N3O6P3] and 2,3-naphthalenediol [4,4,6,6-tetrakis(4-fluorophenoxy)-2,2-(1,2-naphthalenedioxy)-1,3,5,2,4,6- cyclophosphazene, (2), C34H22F4N3O6P3] contain an almost planar N3P3 core which lies perpendicular to the planar five-membered spiro group. The F atoms of the phenoxy groups are involved in the formation of weak intermolecular hydrogen bonds giving rise to dimeric networks in (1) and three-dimensional networks in (2).