Bis(2-methyl-8-hydroxyquinoline) Gallium Chloride (GaMq2Cl) has been synthesized and characterized by X-ray crystallography. It is known from X-ray diffraction data on single crystals that the crystals of GaMq2Cl were monoclinic, space group C2/c, a = 28.701 A, b = 9.5405 A, c = 15.1434 A, Z = 8. Its thermal stability, electron structures and structural stability were investigated by TG analysis and quantum chemical calculations. The complex was a thermally stable material, with decomposition temperature being 348 degrees C. The electron-transfer property of GaMq2Cl is of advantage over hole-transfer property. Under UV excitation at 365 nm, the complex emits blue fluorescence with the maximum emission peak at 471 nm. Finally, blue-green light-emitting devices using this complex as the emissive layer were also fabricated and investigated, with emission wavelength at 502 nm. The results promote GaMq2Cl as a good candidate for luminescent material.