Pure titania (TiO2) and carbon containing titania(C-TiO2) thin films were prepared by reactive sputtering in argon-oxygen plasma at 100 degrees C. The as-deposited thin films were amorphous and subsequently annealed at various temperatures of 280-800 degrees C in air and H-2 atmosphere. The effects of annealing on the films were systematically studied in terms of phase transformation, activation energy, crystallinity, oxygen vacancies and their photocatalytic properties. The as-deposited TiO2 transforms to anatase at a much lower temperature than the C-TiO2. At the same temperature, the H-2-annealed films achieve better crystallinity than the air-annealed films. The activation energies of phase transformation from amorphous to anatase are 180 and 168 kJ/mol for the air- and the H-2-annealed pure TiO2 films, respectively. The result also shows that the C-TiO2 requires higher temperature or more energy for phase transformation than the pure TiO2. (c) 2012 Elsevier B.V. All rights reserved.