In this thesis the TiO 2 /hydroxyapatite (HAP) nanocatalyst was prepared by sol–gel method. This catalyst was doped with Cu(II) and Cu(0) by impregnation and chemical reduction methods. The nanocatalysts were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDX), UV-Vis spectroscopy and transmission electron microscopy (TEM). The photocatalytic activity of the nanocatalysts were evaluated by photocatalytic oxidation of Acid Orange (II)under ultraviolet (UV) and visible (Vis) irradiations. Photocatalyticresults proved that doping of TiO 2 with Cu(II) and Cu (0) enhanced the TiO 2 photocatalytic activity towards Acid Orange (II) photodegradation under UV and Vis irradiation.The reaction parameters such as amount of the catalyst, initial concentration ofAcid Orange (II), pH of the solution, weight percent of Cu(II) were optimized. In the second part of this thesis, the application of Co-Mn nanocatalystwas studied in the oxidation of anthracene to anthraquinone. The results of the reaction were studied by gas chromatography and the performance of nanocatalyst was proved. The reaction parameters such as amount of the catalyst, reaction time, temperature and pressure of oxygen were optimized.