Dinickel(II) silicon bis-[diphosphate(4-)], Ni(2)Si(P(2)O(7))(2), is isotypic with other phosphates of the formula M(2)Si(P(2)O(7))(2) (M = Co, Cd). All atoms except Si (site symmetry 2) are found in general positions. Ni(2)O(10) dimers formed from edge-sharing NiO(6) octa-hedra are linked by corners and O-P-O bridges, forming slabs parallel to (100), which are in turn inter-connected by O-Si-O contacts.