A single-crystal X-ray diffraction analysis has been performed on LiNdP4O12synthesized by the flux method. The crystal belongs to monoclinic system, with space group C2/c, z=4, and cell parameters α= 16.486?, b = 7.073 ?, c =9.775? and β = 126.23°. A full-matrix, least square refinement gave R = 0.054, Rω= 0.050 for 1251 independent reflections. An absorption and secondary extinction refinement gives final R = 0.048. Rω = 0.043. The basic structural units are helical ribbons, (PO3)n, formed by corner-sharing of PO4 tetrahedra. The NdO8 dodecahedra are isolated from each other in the sense that they do not share any O atoms.