Pure alpha-MnO2 nanofibers with multiple branches were prepared through a simple refluxing method in the absence of catalysts or surfactants as templates. The synthetic procedure was based on the use of MnO4- to oxidize Mn2+ under a weak acidic condition. A two-step epitaxial coalescence for the formation of this complex architecture was revealed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). First of all, the small nanofibers coalesced together through the (110) plane to form larger monocrystalline nanofibers, which then attached one by one through two of (110) and {211} planes, resulting in the final multiple branched architectures. (c) 2005 Elsevier B.V. All rights reserved.