In-situ growth of titania nanoparticles in poly (ethylene terephthalate) (PET) nanofibers has been successfully achieved by combining sol-gel method and electrospinning process. Titania precursor. tetra-n-butyl titanate (TBT), was firstly hydrolyzed in trifluoroacetic acid (ITA), and then blend with a solution of PET in mixture of trifluoroacetic acid/dichloromethane (TFA/DCM) to form a homogeneous solution for electrospinning. Titania nanoparticles in-situ generated in the electrospun nanofibers via a hydrothermal treatment process at 70 degrees C-90 degrees C. The morphology and crystallinity of PET/TiO(2) hybrid nanofibers were investigated using TEM and DSC.The results showed that titania nanoparticles of anatase phase with an average diameter of about 10 nm in-situ generated both inside and on the surface of PET electrospun nanofibers. The reversible networks formed between titania nanoparticles and PET macromolecular chains led to considerable decrease of PET crystallinity. (C) 2009 Elsevier B.V. All rights reserved.