Mesostructured iron oxides(MIOs) were nanocasted from a plugged hexagonal templated silica(PHTS)with a Brunauer-Emmett-Teller(BET) surface area of 694 m2/g.Results of X-ray diffraction(XRD),transmission electron microscopy(TEM) and N2 adsorption-desorption suggest that the nanocasted MIOs are synthetic hematite(α-Fe2O3) with a wormhole-like mesoporous network.As(Ⅴ) adsorption test shows that the selected MIO-—MIO-500(calcinated at 500℃) with a BET surface area of 82 m2/g has a maximum adsorption capacity of 5.39 mg/g for As(Ⅴ),which is 2.5 times as large as that of natural hematite adsorbent.The study suggests that MIOs could be potentially used as the adsorbent of As(Ⅴ) in wastewater.