Long chain protonic acid (dodecylhydrogen sulfate-DHS) along with small molecule acid (sulfuric acid-H2SO4) was introduced as dopants in polyaniline salt (PANI-H2SO4-DHS), hereafter referred as PANI, via aqueous/emulsion polymerization pathway of aniline. Polyaniline salt-acetylene black composites (PANI-AB) were prepared in one-step via aqueous/emulsion polymerization pathway using various amounts of acetylene black (AB). Formation of PANI and PANI-AB was confirmed from infrared and X-ray diffraction patterns. The highest conductivity obtained for PANI-AB composite was 6.2 S cm(-1), which is slightly higher than that of PANI (1.3 S cm(-1)). PANI prepared by aqueous polymerization pathway showed nano fibres with diameter of 10-30 nm. Use of 5 wt% of AB with respect to the amount of aniline used in the polymerization reaction of aniline, PANI-AB showed spheres covered nano fibres with high porosity. By increasing the amount of AB to 10 wt%, nano fibres are getting closure, which reduced the porosity. Further increase in the amount of AB to 15 wt%, nano fibres disappear. PANI and PANI-AB were used as electrode materials in symmetric supercapacitor cell. Specific capacitance, Energy and power densities of PANI-AB composite were found to be 157.6 F g(-1)., 15.7 Wh kg(-1) and 600 W kg(-1) respectively. (c) 2013 Elsevier Ltd. All rights reserved.