In situ surface modification of TiO2 and ZnO metal oxide particles has been carried out under hydrothermal conditions within a wide range of temperature and pressure (T=150-400 degrees C; P=up to 20 MPa). The influence of the surfactant and selective doping with active metal ions on the crystal size, morphology, and photocatalytic activity of TiO2 and ZnO particles has been carried out. A systematic characterization of the product has been carried out using powder XRD, FTIR, TGA, SEM/TEM, and UV-vis spectroscopy. Similarly the photocatalytic activity in these metal oxides varies with the size, shape and dopant metals. (C) 2013 Elsevier B.V. All rights reserved.