Highly robust composite photocatalyst (WO3/MIL-53(Fe)) was synthesized and characterised. WO3/MIL- 53(Fe) exhibits remarkable photocatalytic efficiency for reduction of Cr(Vi) and oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) organochlorinated herbicide. After 240 min sunlight irradiation, only ~30% reduction ratio of Cr(VI) was recorded in the presence of WO3. However, about 70% and 94% Cr(Vl) reduction were achieved in the presence of MlL-53(Fe) and WO3/MIL-53(Fe), respectively. The removal efficiency proceeds more rapidly in the binary mixture of 2,4-D and Cr(VI) than in the single component system, indicating synergetic effect between the photooxidation and reduction reactions. 02•- played a key role in the reduction of Cr (VI) and h+ is confirmed to be the dominant active species in the degradation of 2,4-D. [ABSTRACT FROM AUTHOR]