The crystal structure of the quaternary compounds CuFe 2 AlSe 4 and CuFe 2 GaSe 4 , belonging to the system I-II 2 -III-VI 4 , were characterized using X-ray powder diffraction data. Both compounds crystallize in the tetragonal space group I 4 2m (No. 121), Z = 2, with unit cell parameters a = 5.609(1) Å, c = 10.963(2) Å for CuFe 2 AlSe 4 and a = 5.6165(3) Å, c = 11.075(1) Å for CuFe 2 GaSe 4 . These compounds are isostructural with CuFe 2 InSe 4 , and have a normal adamantane stannite structure.