An　open-framework　zincophosphate,　[C(4)N(3)H(16)][Zn(4.5)(PO(4))(4)]　1,　has　been　hydrothermally　synthesized　and　characterized　by　single-crystal　X-ray　diffraction.　It　crystallizes　in　the　tetragonal　space　group　P　(4)　over　bar　with　a　=　14.512(5),　c　=　8.914(3)　A,　V　=　1877.3(11)　A(3),　C(4)H(16)N3O(16)P(4)Zn(4.50),　M(r)　=　780.24,　Z　=　4,　D(c)　=　2.761　g/cm(3),　mu　=　6.103　mm(-1),　F(000)　=　1536,　T　298(2)　K,　R　=　0.0416　and　wR　=　0.0816.　In　the　structure,　ZnO(4)　and　PO(4)　tetrahedra　are　linked　to　each　other,　forming　four-membered　rings　which　are　connected　variably　to　form　two　secondary　building　units　(SBUs).　The　SBUs　are　connected　so　as　to　generate　two　chains　along　the　c　axis,　which　are　further　linked　together　alternatively　via　common　oxygen　atoms　(Zn-O-P)　giving　rise　to　8-ring-channels　in　the　[001]　direction,　and　the　protonated　guest　diethylenetriamine　(DETA)　molecules　sit　in　the　middle　of　these　channels.　Other　characterizations　are　also　described　by　elemental　analysis,　thermal　analysis　and　IR　and　fluorescent　spectra.