In this paper, core/sheath TiO2/SiO2 nanofibers with tunable sheath thickness were directly fabricated via a facile co-electrospinning technique with subsequent calcination at 500 degrees C. The morphologies and structures of core/sheath TiO2/SiO2 nanofibers were characterized by TGA, FESEM, TEM, FTIR, XPS and BET. It was found that the 1D core/sheath nanofibers are made up of anatase-rutile TiO2 core and amorphous SiO2 sheath. The influences of SiO2 sheath and its thickness on the photoreactivity were evaluated by observing photo-degradation of methylene blue aqueous solution under the irradiation of UV light. Compared with pure TiO2 nanofibers, the core/sheath TiO2/SiO2 nanofibers performed a better catalytic performance. That was attributed to not only efficient separation of hole-electron pairs resulting from the formation of heterojunction but also larger surface area and surface silanol group which will be useful to provide higher capacity for oxygen adsorption to generate more hydroxyl radicals. And the optimized core/sheath TiO2/SiO2 nanofibers with a sheath thickness of 37 nm exhibited the best photocatalytic performance. (C) 2013 Elsevier Ltd. All rights reserved.