A new polycation-type phosphate of H{[Na-(H 2 O) 3 ] 6 F}(PO 4 ) 2 • 2(H 2 O) (FNPO) was synthesized by a mild hydrothermal method. FNPO crystallizes in the cubic space group of Fd � 3c with cell parameters of a = 27.778 Å and Z = 32. In the structure of FNPO, every sodium ion is six-fold coordinated to five water molecules and one fluoride ion in forming electroneutral [NaF(H 2 O) 5 ] octahedra, while one kind of super octahedral polycation-type {[Na(H 2 O) 3 ] 6 F} 5 + complexes with center anion of Fis constructed by six [NaF(H 2 O) 5 ] octahedra via the sharing of their terminal fluoride ion and water molecules. Besides counter cation of {[Na(H 2 O) 3 ] 6 F} 5 + complexes, all the other (PO 4 ) 3À and water molecules are in a discrete arrangement with sole connection of hydrogen-bond interaction with {[Na-(H 2 O) 3 ] 6 F} 5 + complexes in forming [101]-oriented pseudo-lines, while each line is hydrogen-bonded to six adjacent lines in generating the three-dimensional structure of FNPO. Benefitted by this polycation-type structure, FNPO was characterized by a deep ultraviolet transparency.