Nickel oxide nanoparticles supported activated carbon (NSAC) photocatalyst was successfully prepared using a cost-effective microwave irradiation method. The earned UV light-sensitive NSAC composites were characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, High-resolution scanning electron microscope with energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface area analyzer. Optical properties of NSAC 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 NiO. 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 NSAC composites showed imposing photocatalytic enrichment over pure NiO. The coordinated blending of the oxygen vacant sites, structural defects of NiO 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 NSAC. © 2014 Balaban Desalination Publications. All rights reserved.