Single crystals of the title compound, NaTb(PO3)4, were obtained by solid-state reaction. This compound belongs to type II of long-chain polyphosphates with the general formula A I B III(PO3)4. It is isotypic with the NaNd(PO3)4 and NaEr(PO3)4 homologues. The crystal structure is built up of infinite crenelated chains of corner-sharing PO4 tetrahedra with a repeating unit of four tetrahedra. These chains, extending parallel to , are linked by isolated TbO8 square antiprisms, forming a three-dimensional framework. The Na+ ions are located in channels running along  and are surrounded by six oxygen atoms in a distorted octahedral environment within a cut-off distance <2.9 Å.