We present here a facile one-pot surfactant-free solvothermal route to synthesize hierarchical BiOI microspheres assembled from nanosheets at 120 degrees C for 16 h. The as-synthesized BiOI microspheres could be topochemically converted into hollow hierarchical Bi2WO6 ones built by nanoplates for the first time under hydrothermal condition because of the analogies of crystal structures. The transformation process of hierarchical BiOI microspheres to hollow Bi2WO6 ones was surveyed through XRD analyses and FE-SEM observations of the intermediates at different reaction stages. Rhodamine B (RhB) was selected as pollutant model and visible-light-driven photocatalytic activities of hierarchical BiOI and Bi2WO6 microspheres under the same measurement conditions were comparatively studied. As a result, the photocatalytic activities of BiOI obviously outshone Bi2WO6. The present study not only develops a new method for fabricating hierarchical architectures but also provides some useful information on relative visible-light-responding photocatalytic activity of hierarchical BiOI and Bi2WO6 microspheres. (C) 2013 Elsevier B.V. All rights reserved.