Polyaniline nanodisks have been synthesized successfully by the chemical oxidation polymerization of aniline by a self-assembly process without the use of any acid. The thickness and lateral dimensions of the polyaniline nanodisks are in the range of 20-30 nm and 1-2 mu m, respectively. The influence of synthetic parameters, such as the concentration of ammonium peroxydisulfate and pH, on the morphologies of polyaniline nanostructures have been investigated.