ZnGa 2 O 4 was synthesized from Ga(NO 3 ) 3 and ZnCl 2 via a rapid and facile microwave-assisted hydrothermal method. The photocatalytic properties of the as-prepared ZnGa 2 O 4 were evaluated by the degradation of pollutants in air and aqueous solution under ultraviolet (UV) light illumination. The results demonstrated that ZnGa 2 O 4 had exhibited efficient photocatalytic activities higher than that of commercial P25 (Degussa Co.) in the degradation of benzene, toluene, and ethylbenzene, respectively. In the liquid phase degradation of dyes (methyl orange, Rhodamine B, and methylene blue), ZnGa 2 O 4 has also exhibited remarkable activities higher than that of P25. After 32min of UV light irradiation, the decomposition ratio of methyl orange (10ppm, 150mL) over ZnGa 2 O 4 (0.06g) was up to 99%. The TOC tests revealed that the mineralization ratio of MO (10ppm, 150mL) was 88.1% after 90min of reaction. A possible mechanism of the photocatalysis over ZnGa 2 O 4 was also proposed.