A new method for forming stable polyaniline nanofiber colloids uses electrostatic repulsion to maintain dispersion of the nanofibers and prevent aggregation during synthesis of the nanofibers. The colloidal suspensions are formed directly from the reactants in solution maintained at a pH of about 1.0 to about 4.0 and a temperature of about 10° C. to about 100° C. with minimal or no stirring. Also set forth are new methods for forming ultrathin films of polyaniline nanofibers via self-assembly.