In this work, the porous structure and the Cr(VI) removal abilities of the magnetite (Fe3O4) nanopowder prepared by one-pot solvothermal reaction of Fe-urea complex ([Fe(CON2H4)(6)](NO3)(3)) were investigated. Low-angle X-ray diffraction (XRD), nitrogen adsorption-desorption measurements, and transmission electron micrograph (TEM) observations show that the Fe3O4 has a mesoporous structure with an average pore size of 5.3 nm and BET surface area of 120 m(2)/g. The removal of gaseous species including CON2H4, NO, NO2 and O-2 during the formation of the Fe3O4 are considered to be the most probable reason for the formation of mesoporous structure. The adsorption behavior of Cr(VI) on the mesoporous Fe3O4 can be well described by Langmuir adsorption model, and the maximum adsorption capacity for Cr(VI) is estimated to be 15.4 mg/g. (C) 2011 Elsevier B.V. All rights reserved.