Polyaniline (PANI) based nanocomposites filled with ZnO nanorods were prepared by the chemical oxidative method of the aniline in acid medium with ammonium peroxydisulphate (APS) as an oxidant. The composition, morphology and structure of the polymer and the nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV-vis spectroscopy and electrical conductivity. The characteristic FTIR peaks of PANI were found to shift to higher or lower wave number in PANI-ZnO composites due to formation of H-bonding. Different amounts of ZnO nanorods were used to verify this effect on the characteristics of the synthesized materials. These observed effects have been attributed to interaction of ZnO nanorods with PANI molecular chains. XRD results revealed that the crystallinity of PANI was more pronounced after addition of nanorods, while the intensity of the peaks increased by addition of ZnO nanorods. Electrical conductivity of the PANI-ZnO nanocomposite film was found to be smaller than that of the PANI film. The decrease of electrical conductivity in PANI-ZnO films as compared to PANI was attributed to the interfaces formed between oxygen of ZnO nanorods and hydrogen of PANI. Also, TGA results showed that the decomposition of the nanocomposite was less than that of pure polyaniline which confirms the successful fabrication of products. These conductive polymers can be used in commercial paints as an additive.