A solvent-free mechanochemical route for the synthesis of polyaniline has been developed. Reactions between anilinium salts, such as anilinium chloride, anilinium sulfate, and anilinium. camphorsulfonic acid and the oxidant, ammonium peroxydisulfate, result in polyaniline formation on ball-milling the reactants. Spectroscopic studies indicate that polyaniline is formed in its doped, conductive emeraldine oxidation state. By varying the aniline-to-oxidant ratio, a yield of up to 65% can be achieved. The polyaniline has a relatively high surface area of 69.7 m(2)/g using the Brunauer-Emmett-Teller method. A typical bimodal molecular weight distribution is observed for the polyaniline product. Resistance measurements indicate that 1 h is sufficient for the solid-state reactions to reach completion.