Single crystals of gadolinium-sodium polyphosphate NaGd(PO3)(4) were grown tor the first time using a flux method and characterized by X-ray diffraction. This phosphate crystallizes in it monoclinic system with P2(1)/n space group and with the following unit-cell dimensions: a = 9.767(3) angstrom, b = 13.017(1) angstrom, c = 7.160(2) angstrom, beta = 90.564(5)degrees, V = 910.3(4) angstrom(3) and Z=4. The crystal structure was solved from 3451 X-ray independent reflections with final R(F-2) = 0.0219 and R-w(F-2) = 0.056 refined with 164 parameters (F-0(2) > 4 sigma(F-0(2))). The atomic arrangement can be described as a long chain polyphosphate organization. Two infinite (PO3) proportional to chains with a period of eight tetrahedra run along the [0 1 1] direction. The structure of NaGd(PO3)(4) consists of GdO8 polyhedra sharing oxygen atoms with phosphoric group PO4. Each Na+ ion is bonded to eight oxygen atoms. (C) 2005 Elsevier Ltd. All rights reserved.