Three new diamond-like compounds with the formula of I 2 −II−IV−VI 4 (I=Cu; II=Mg; IV=Si, Ge; VI=S, Se) have been synthesized via traditional high-temperature solid-state reactions and structurally characterized by single crystal X-ray diffraction analysis. All the three compounds crystallize in the space group Pmn2 1 in the wurtzite-type superstructure with a=7.563(4), b=6.448(3), c=6.179(3)Å, Z=2 for Cu 2 MgSiS 4 (1); a=7.953(5), b=6.797(4), c=6.507(4)Å, Z=2 for Cu 2 MgGeS 4 (2); a=7.638(4), b=6.515(4), c=6.225(3)Å, Z=2 for Cu 2 MgSiSe 4 (3). All atoms in these compounds are tetrahedrally coordinated. Optical diffuse reflectance UV/Vis/NIR spectra indicate that compounds 1 and 2 have the band gaps of 3.20 and 2.36eV, respectively. Electronic structure calculations using the CASTEP code indicate that they are all direct band gap compounds.