Leaf-like hierarchical polyaniline (PANI) structure with interlaced nanofibers on the surface was prepared by chemical oxidation polymerization of aniline assisted by sodium dodecyl benzene sulfonate (SDBS). The chemical structure and the composition of the leaf-like PANI obtained were characterized by FTIR, UV-vis, XRD and XPS. In order to investigate the formation mechanism of such micro/nanostructures, some micro/nanostructures of PANI polymerized at different polymerization times were synthesized and observed for comparison. The results show that the PANI micro/nanostructures originate from PANI microleaves due to SDBS as soft template, which then covered with interlaced nanofibers on the surface. The leaf-like PANI micro/nanostructures exhibit good hydrophobic property with a water contact angle of 134.3 degrees resulted from the hydrophobic long dodecyl groups of SDBS dopant. Crown Copyright (C) 2013 Published by Elsevier Inc. All rights reserved.