This work focuses on the development of electrically conducting carbon nanofiber (CNF) mats obtained by incorporating different amounts of heteropolyacids (HPAs) viz., silicotungstic acid (SiWA) and silicomolybdic acid (SiMoA) into polyacrylonitrile (PAN) precursor by electrospinning technique. Electron and transmission microscopic studies confirmed the cylindrical morphologies of CNFs with diameters ranging between 100 to 300 nm after carbonization at 1000 degrees C. Electrical conductivity of the CNF mats increased with increasing concentrations of HPAs. The optimal HPA concentration of 5 wt.% seems to be responsible for enhancements of morphological and physico-chemical properties of developed carbon nanofibers. X-ray diffraction proved the increase in intensity due to the presence of HPA in the matrix. TGA was used to understand the thermal behavior of the CNFs. (C) 2009 Elsevier B.V. All rights reserved.