CsHoO2 is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Cs1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Cs–O bond lengths are 3.09 Å. Ho3+ is bonded to six equivalent O2- atoms to form edge-sharing HoO6 octahedra. All Ho–O bond lengths are 2.34 Å. O2- is bonded in a 6-coordinate geometry to three equivalent Cs1+ and three equivalent Ho3+ atoms.