KReO4 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight equivalent O2- atoms. There are four shorter (2.86 Å) and four longer (2.95 Å) K–O bond lengths. Re7+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Re–O bond lengths are 1.76 Å. O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Re7+ atom.