Photocatalytic activity of mixtures of anatase and rutile titania nanoparticles, both bare and treated via capillary condensation of a silica precursor. was investigated by following photodegradation of methylene blue by ultraviolet light in an aqueous solution. The best observed activity for the physically mixed nanoparticles was seen at an anatase to futile mass ratio of 4: 1. This mixture was subject to capillary condensation of tetraethyl orthosilicate (TEOS) at various saturation ratios, followed by reaction of TEOS to form silica. Treatment at a saturation ratio of 1.2 improved photoactivity over that of the physical mixture, a result attributed to enhanced interphase connectivity and increased methylene blue adsorption onto silica. (C) 2009 Elsevier Inc. All rights reserved.