Aims: The purpose of this study was to remove azonium compound using the photocatalytic property of nickel (Ni)-doped titanium dioxide (TiO 2 ) nanoparticles coated on Iranian natural zeolite. Materials and Methods: Nickel-doped TiO 2 nanoparticles with the molar ratios of 0, 0.17, 2, 9% Ni/TiO 2 were prepared via the sol-gel process and coated on Iranian natural zeolite clinoptilolite (CLI). Afterward, X-ray diffraction, scanning electron microscopy and inductively coupled plasma studies were conducted to describe Ni and titanium. Photocatalytic removal of azo dye in concentrations of 25 and 50 mg/L was performed by fixing the composite under ultraviolet irradiation. Results: TiO 2 nanoparticles in both the anatase and rutile phases were obtained via the sol-gel method with the ratios of 86.33%, (34.44 nm particle size) and 13.67% (18 nm particle size) and were then coated on Iranian natural CLI zeolite. The results indicated that the photocatalytic removal efficiency of the 9% Ni/TiO 2 -CLI samples, in which the azo dye concentrations were 25 and 50 mg/L, was 93% and 79% at 160 min. In addition, the composition of the 9% Ni/TiO 2 -CLI possessed the greatest removal rate difference of azo dye at the concentrations of 25 and 50 mg/L. Conclusion: Application of Iranian CLI as a substrate is the most cost-effective way to increase the photocatalytic activity. Furthermore, adding Ni to TiO 2 can increase the photocatalyst removal efficiency of azonium compound.