Novel　poly(pyrrole-co-aniline-2-sulfonic　acid)　(PPYAS)　nanoparticles　were　prepared　via　chemical　oxidative　polymerization　of　pyrrole　and　aniline-2-sulfonic　acid　in　different　aqueous　solutions　without　any　external　additives.　The　morphology,　structure　and　electroconductivity　of　the　HCl-doped　particles　were　studied　by　changing　the　molar　ratio　of　the　oxidant　and　monomers,　and　the　solvent　for　polymerization.　It　was　found　that　the　yield,　mean　diameter　and　electrical　conductivity　of　the　resulting　particles　varied　strongly　with　the　molar　ratio　of　the　components.　The　nanoparticles　exhibit　a　minimum　mean　diameter　of　around　62　nm,　and　good　self-stability　because　of　the　introduction　of　sulfo　groups　into　the　chains　of　the　copolymer.　The　preparation　affords　yield　of　up　to　85%,　and　the　HCl-doped　copolymer　salts　possess　an　electroconductivity　between　0.　68　and　0.　2　S/cm,　depending　on　the　fraction　of　anilinesulfonic　acid.　©　2010　Springer-Verlag.