Eu2SeO2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu3+ is bonded in a 4-coordinate geometry to four equivalent Se2- and four equivalent O2- atoms. All Eu–Se bond lengths are 3.43 Å. All Eu–O bond lengths are 2.29 Å. Se2- is bonded in a body-centered cubic geometry to eight equivalent Eu3+ atoms. O2- is bonded to four equivalent Eu3+ atoms to form a mixture of edge and corner-sharing OEu4 tetrahedra.