This study is aimed at investigating the effect of different oxidants on properties of polyaniline/single walled carbon nanotubes (PANI/SWCNT) composites and scrutinizing a suitable oxidant to improve the properties of composites. PANI/SWCNT composites were fabricated via ultrasonically initiated in-situ chemical polymerization technique using four different oxidants; hydrogen peroxide (H2O2), ammonium peroxidisulphate ((NH4)(2)S2O8), potassium dichromate (K2Cr2O7) and potassium iodate (KIO3). Percent yield (97%), molecular weight (45532 g mol(-1)) and electrical conductivity (0.835 S cm(-1)) were found maximum for composite prepared in the presence of H2O2. Structural confirmation of PANI and charge transfer complex formation between PANI and SWCNT were confirmed by fourier transform infrared spectroscopy, UV-visible spectroscopy and X-ray diffraction spectroscopy. Thermogravimetric analysis verified that the PANI/SWCNT composite synthesized using H2O2 had maximum thermal stability with least thermal degradation (similar to 28%). Minimal thermal transitions of the composite were also observed for same composite by differential scanning calorimetry. Scanning electron microscopic images of PANI/SWCNT composites revealed that SWCNT were properly dispersed in PANI matrix when H2O2 was used. Above results provide the valuable suggestion that; H2O2 is a promising oxidant to enhance structural, thermal, electrical and microscopic properties of composites. (C) 2016 Elsevier B.V. All rights reserved.