The　room　temperature　electrical　conductivity　of　polyaniline　(PANI)　was　found　to　increase　remarkably　after　it　was　heated　in　tetrahydrofuran　(THF)　with　refluxing　for　a　certain　period　and　then　doped　with　methanesulfonic　acid　(MSA).　The　enhanced　electrical　conductivity　of　PANI　was　attributed　to　a　partially　cross-linked　network　generated　via　the　formation　of　new　chemical　bonds　between　adjacent　PANI　chain　segments　during　thermal　treating,　which　may　shorten　the　inter-chain　distance　and　facilitate　inter-chain　transition　of　charge　carriers　in　doped　PANI.　During　the　refluxing,　the　moderate　dissolving　power　for　PANI　as　well　as　a　much　lower　boiling　point　of　THF　were　considered　to　have　a　unique　effect　on　the　formation　of　such　partially　cross-linked　network　in　PANI.　As　a　comparison,　PANI　treated　in　poor　solvents　like　methanol　(or　ethanol)　and　PANI　treated　in　dimethyl　formamide　(DMF),　which　is　a　better　solvent　than　THF　but　has　higher　boiling　point,　did　not　show　an　obviously　increased　electrical　conductivity.　Study　on　X-ray　diffraction　(XRD)　analysis　of　PANI　after　refluxing　showed　that　crystallinity　decreased　gradually　with　the　increase　of　cross-linking　degree,　but　the　inter-chain　cross-linking　probably　occurred　first　in　crystalline　region　and　then　in　the　amorphous　region.　Electrical　conductivity　of　PANI　decreased　after　it　was　refluxed　with　THF　for　an　extended　period　due　to　the　decreased　crystallinity　and　doping　in　PANI.　Copyright　(C)　2010　John　Wiley　&　Sons,　Ltd.