Controlled BiOBr hierarchical nanostructures (HNs) have been fabricated by a polyvinyl pyrrolidone (PVP) assisted hydrothermal method. The as-synthesized samples have a tetragonal phase and are composed of primary plate-like nanostructures with a thickness from 10 to 300 nm. Hall Effect displays the new material is N-type semiconductor. The possible reaction and growth mechanism is also discussed based on contradistinctive experimental results. Concentration of PVP in the reaction mixture plays a key role for controllable structures and morphologies because PVP can attach on the (012) plane of the BiOBr HNs selectively and insulate the growth of this plane. In addition, PVP is used to manipulate the band gaps of products. The as-prepared BiOBr HNs possess narrow band gaps (1.75-2.5 eV), large surface areas, and uniform particle size. Moreover, photocatalytic degradation efficiencies of methyl orange (MO) of BiOBr samples are detected and the as-obtained results show an excellent photocatalytic capacity of BiOBr HNs under irradiation of visible light (lambda >= 420 nm). (C) 2013 Elsevier B.V. All rights reserved.