Polystyrene (PS)/Titanium dioxide (TiO2) composite nanofibers were prepared by electrospinning of PS/TiO2 solution in N,N-dimethylformamide (DMF). The effect of PS and TiO2 concentration on the morphology and thermal properties of the fibers was investigated. The resultant fibers were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology and thermal properties of PS nanofibers with and without TiO2 were compared. The composite fibers had a size range of about 400-1200 nanometer in diameter with jaggy morphology which increases its surface-to-volume ratio. Different aspects of thermal properties including thermal decomposition temperatures, glass transition temperature, and residue in PS/TiO2 composite fibers at different TiO2 loading of electrospun fibers are evaluated. POLYM. ENG. SCI., 53:2407-2412, 2013. (c) 2013 Society of Plastics Engineers