Photocatalysis is one of the most sufficient methods used for the removal of organic contaminants from wastewater. In this study, nickel (Ni) doped Carbon nanotubes (CNTs) nanocomposites were tested as a photocatalyst for the methyl orange (MO) dye degradation under irradiation of visible light. Ni doped CNTs nanocomposites were synthesized by using the reduction method. The prepared Ni doped CNTs nanocomposites were characterized using X-ray diffraction (XRD), Fourier-transformed infrared (FTIR)  and UV-visible spectroscopy. The degradation of MO dye was carried out by using different amounts (0.05 g, 0.1 g and 5 g) of Ni doped CNTs (with and without acid) at different time intervals.  From experiments, it was observed that catalyst Ni doped CNTs without acid showed the highest photocatalytic efficiency for the degradation of MO dye as compared to the catalyst with acid. It was also observed that this efficiency could be enhanced by increasing the amount of the catalyst. Maximum photodegradation (83%) of MO dye was obtained in just 5 minutes when 5 g of the photocatalyst (without acid) was used .