Electrically conductive dodecyl-benzene-sulfonic-acid (DBSA) doped polyaniline (Pani) nanocomposites were prepared with multi-walled carbon nanotubes (MWCNTs) by in situ oxidative polymerization of aniline in the presence of different amounts of MWCNTs. The stability of the nanocomposites in terms of DC electrical conductivity retention was studied in ambient atmosphere by isothermal accelerated aging and cyclic accelerated aging techniques. The MWCNT/Pani nanocomposites were observed to be thermally more stable under ambient environmental conditions than Pani. Such nanocomposites with high thermal stability may find a place as future materials for the replacement for Pani.