FeGe2 is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Fe is bonded in a 10-coordinate geometry to two equivalent Fe and eight equivalent Ge atoms. Both Fe–Fe bond lengths are 2.47 Å. All Fe–Ge bond lengths are 2.55 Å. Ge is bonded in a 5-coordinate geometry to four equivalent Fe and one Ge atom. The Ge–Ge bond length is 2.63 Å.