KSbP 2O 8 crystallizes in the rhombohedral system, space group R overline3, with a = 4.7623(4) Å, c = 25.409(4)Å, and Z = 3. The structure was determined from 487 reflexions collected on a NONIUS CAD4 automatic diffractometer with Mo K-α radiation. The final R index and weighted Rw index are 0.030 and 0.038, respectively. This structure is built up from layers of SbO 6 octahedra and PO 4 tetrahedra sharing corners. These (SbP 2O -8) n layers are very similar to the (ZrP 2O 2-8) n layers in the well-known α-ZrP compound.