TiO2 and its hybrid TiO2-Fe3O4 NPs were prepared, and doped with Ag, or Au NPs to yield TiO2-Fe3O4-Ag NPs and TiO2-Fe3O4-Au NPs. The photo-catalytic oxidation of phenols by the above materials were analyzed under both solar and UV light. For TiO2-Fe3O4-Ag NPs and TiO2-Fe3O4-Au NPs considerable visible light photo-oxidation was observed, while for other nano-materials UV-light energy required. The materials having Fe3O4 were reused after isolation by magnets. The oxidation rate decreases from phenol to 2,4,6-trichlorophenol in agreement with the Hammett plot, and follows first order kinetics in the substrate, for which a possible mechanism is proposed. The effect of pH, and solvents were also analyzed in the oxidation. To further support our kinetics experiments, Density functional theory (DFT) calculation were performed to predict the rate limiting step of phenol oxidation to yield benzoquinone. (C) 2015 Elsevier B.V. All rights reserved.