In this study, morphological, thermal and dielectric properties of chemically synthesized polyaniline (PANI) and its cerium(III)-nitrate-hexahydrate (Ce(NO3)(3).6H(2)O) doped composites with various doping levels were investigated. Characteristic bands of emeraldine salt (ES)-form of PANI was clearly observed in UV-visible (UV-vis)and Fourier transform infrared (FTIR) spectroscopies. Thermal analyses carried out by Differential scanning calorimetry (DSC) indicated that there was a glass transition at about 70 degrees C and the doping process increased thermal stability of the polymer. In the surface morphologies examined by scanning electron microscopy (SEM), various microstructures depending on the doping level were observed. Real dielectric constant exhibited a significant decrease due to the increase in the doping level especially at higher frequencies. Conductivity mechanisms of PANI and its composites were investigated by universal power law as conventional models could not provide a complete picture for all the samples. Dramatic increases up to 45, 35 and 30 times in the conductivity of 10% doped PANI were observed for 300, 350 and 400K, respectively. (C) 2012 Elsevier BM. All rights reserved.