The decolorization of Orange II was studied under visible light using bimetallic Cu-Ni/TiO 2 prepared via precipitation method. Cu:Ni mass composition of 9:1 was prepared and the effect of calcination temperature on the Orange II removal was investigated. The raw photocatalysts were activated by calcination at three different temperatures (180°C, 200°C and 300°C) for 1 hour duration. Photocatalysts were characterized using Thermogravimetric Analysis (TGA), Fourier-Transformed Infra red spectroscopy (FTIR), Powder X-Ray diffraction (XRD) and Field-Emission Scanning Electron Microscopy-Energy Dispersive X-ray (FESEM-EDX). The photocatalytic degradation of Orange II was conducted under the irradiation of visible light (500 W halogen lamp) at pH 6.8. The extent of degradation for Orange II with initial concentration of 50 ppm was monitored using UV-vis spectroscopy and TOC analysis was conducted at the end of the reaction. Results showed that complete Orange II removal was achieved for Cu:Ni/TiO 2 photocatalysts calcined at 180°C, and 200°C Photocatalyst calcined at 180°C showed the best performance with 100the lowest TOC value of 16.1 ppm. © 2011 IEEE.