This　paper　reports　that　the　Schottky　junctions　between　low　work　function　metals　(e.g.　Al　and　In)　and　doped　semiconducting　polymer　pellets　(e.g.　polyaniline　(PANI)　microsphere　pellet　and　polypyrrole　(PPy)　nanotube　pellet)　have　been　prepared　and　studied.　Since　Ag　is　a　high　work　function　metal　which　can　make　an　ohmic　contact　with　polymer,　silver　paste　was　used　to　fabricate　the　electrodes.　The　Al/PANI/Ag　heterojunction　shows　an　obvious　rectifying　effect　as　shown　in　I　-　V　characteristic　curves　(rectifying　ratio　gamma　=　5　at　+/-6　V　bias　at　room　temperature).　As　compared　to　the　Al/PANI/Ag,　the　heterojunction　between　In　and　PANI　(In/PANI/Ag)　exhibits　a　lower　rectifying　ratio　gamma　=　1.6　at　+/-2　V　bias　at　room　temperature.　In　addition,　rectifying　effect　was　also　observed　in　the　heterojunctions　Al/PPy/Ag　(gamma　=　3.2　at　+/-1.6　V　bias)　and　In/PPy/Ag　(gamma　=　1.2　at　+/-3.0　V　bias).　The　results　were　discussed　in　terms　of　thermoionic　emission　theory.