Zinc oxide nanoparticle supported activated carbon (ZSAC) was successfully prepared using a cost effective microwave irradiation method. The earned UV light sensitive ZSAC composites were characterized using powder X-ray diffraction (XRD), high resolution scanning electron microscopy with energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy. The optical properties of ZSAC composites were investigated using UV–Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy, which exposed prolonged light absorption in UV light region and hold better charge separation capability, respectively as compared to pure ZnO. The photocatalytic activity was tested by the degradation of textile dye waste water (TDW) under UV light irradiation. Chemical oxygen demand of TDW was calibrated before and after the photocatalysis experiment under UV light to evaluate the mineralization of wastewater. The results demonstrated that ZSAC composites showed imposing photocatalytic enrichment over pure ZnO and commercial TiO2 (Degussa P25). The coordinated blending of the oxygen vacant sites, structural defects of ZnO along with electron transmission capacity and presence of surface oxygen on AC has led to the lasting light absorption, delayed charge recombination, and sustenance, which favor the enrichment of the photocatalytic activity of ZSAC. © 2014, Akadémiai Kiadó, Budapest, Hungary.