A facile method to prepare polyaniline hollow microsphere was developed using potassium hexacyanoferrate (III) as oxidant for polymerization of aniline in aqueous condition without acid or alkali or organic solvent, and doped polyaniline with electrical conductivity of Ca. 10(-3) S/cm was directly obtained with hexacyanoferrate (II) anion surrounding imine and amine atoms in polyaniline backbone, which was seven orders of magnitude higher than that of polyaniline hollow spheres synthesized in alkaline medium (Ca. 10(-10) S/cm). The hollow spherical structure was formed by a self-assembly process of spherical aniline micelles as shell and inner aniline droplet as core, and nanoscale polydispersed hollow spheres whose diameter varied from 380 nm to 700 nm with a shell thickness from 50 nm to 78 nm were readily obtained. (C) 2011 Elsevier Ltd. All rights reserved.