Polypyrrole(PPy)titania(TiO2) nanocomposites were prepared by an in situ oxidative polymerization method with two different oxidants, namely ammonium persulfate (APS) and ferric chloride. The effects of oxidant type and TiO2 particle loading level on the physiochemical properties of the PPyTiO2 nanocomposites were investigated in details. The intermolecular interactions within the polymer nanocomposites were explored by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). While scanning electron microscopy (SEM) was used to characterize surface morphology, transmission electron microscopy (TEM) revealed the well-dispersed TiO2 nanoparticles in the PPy matrix. The thermogravimetric analysis (TGA) revealed improved thermal stability of PPy with addition of the nanofillers. The nanocomposites prepared by APS oxidation exhibited lower electrical conductivity at room temperature than that of the PPy nanocomposites from FeCl3 oxidation polymerization. Both nanocomposites and pure PPy follow the three-dimensional variable range hopping (VRH) electron conduction mechanism. The frequency dependent dielectric constants of PPyTiO2 nanocomposites were measured in the range of 20 Hz-2 MHz. © 2011 The Electrochemical Society.