Cs2Ga2Se5 was obtained by the reaction of CsN3 with stoichiometric amounts of GaSe and Se at elevated temperature. It forms yellow crystals embedded in a pure orange microcrystalline powder. The crystal structure of Cs2Ga2Se5 was determined by single-crystal X-ray diffraction at 123 K. The compound crystallizes monoclinically in the space group C2/c (No. 15) with a = 15.3911(5) Å, b = 7.3577(2) Å, c = 12.9219(3) Å, β = 126.395(3)°, V = 1177.89(7) Å3, and Z = 4. The structure features one-dimensional chains 1∞[Ga2Se3(Se2)2–], consisting of edge- and corner sharing GaSe4 tetrahedra. Raman spectroscopic measurements reveal vibrational bands of the Se22– units at 236 cm–1, and the bands of Ga–Se vibrations at 254 and 273 cm–1. UV/Vis diffuse reflectance spectroscopy shows the bandgap at about 1.95 eV.