The effects of silica coating on the photocatalytic properties of anatase titanium dioxide (TiO2) were studied by quantitative detection of reactive oxygen species under UV-irradiation, because the surface modification with silica has been practically used to suppress the photocatalytic activity in organic supports. For reactive oxygen species such as superoxide radicals (center dot O-2(-)), H2O2, and OH radicals, the detection methods using MCLA chemiluminescence, lucigenin chemiluminescence, and coumarin fluorescence were employed respectively. By comparing silica-coated TiO2 with uncoated TiO2 powders, the amount of H2O2 detected under UV irradiation was significantly decreased by silica coating. Thus the silica modification suppressed the release of H2O2, which may be the nature of the effect of silica coating for suppressing photocatalytic activity against organic supports. (C) 2012 Elsevier B.V. All rights reserved.