HoSb3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ho3+ is bonded to twelve equivalent Sb1- atoms to form a mixture of face and corner-sharing HoSb12 cuboctahedra. There are six shorter (3.27 Å) and six longer (3.44 Å) Ho–Sb bond lengths. Sb1- is bonded in a 4-coordinate geometry to four equivalent Ho3+ atoms.