Highly crystalline monoclinic bismuth vanadate (BiVO4) nanopowders with crystallite sizes less than 50 nm were obtained by mechanical milling of a stoichiometric mixture of bismuth oxide (Bi2O3) and vanadium pentoxide (V2O5). Different synthesized batches were obtained by varying the preparation times and the number of the tungsten carbide balls (BPR) while keeping constant the jar rotation speed. Annealing treatments were performed on the obtained nanopowders in order to improve the crystalline order and the BiVO4 nanoparticles surface states. Characterizations methods, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with X-ray energy dispersive spectrometer (EDS), Raman spectrometry, FTIR and UV-Vis diffuse reflectance techniques were used to shed light on the structure, morphologies and composition of the obtained nanopowders. Even if monoclinic BiVO4 crystalline structure was stabilized in samples after appropriate annealing, shifts of Raman peak positions after such treatments revealed the occurrence of symmetry distortions in the local structure of the monoclinic phase. (C) 2012 Elsevier B.V. All rights reserved.