High-thermostably ordered mesoporous TiO2/SiO2 nanocomposites are successfully prepared through evaporation-induced self-assembly method combined with ethylenediamine bounding strategy and subsequent high-temperature calcinations (700 degrees C). The prepared samples are characterized in detail by thermogravimetric-differential scanning calorimetry, X-ray diffraction, Raman, transmission electron microscopy and N-2 adsorption. The results indicate that the samples are ordered mesostructure and the presence of SiO2 inhibits the anatase-to-rutile phase transformation at high temperature. Significantly, the experimental results show that the high-thermostably ordered mesoporous TiO2/SiO2 nanocomposites play bifunctional roles on effectively adsorbing As (III) and completely oxidizing higher toxic As (III) to lower toxic As (V) under various pH values by one time. Moreover, after recycling for ten times the composites still keep wonderful photocatalytic and adsorption performance. The subtly nanostructured bifunctional composites will have broad application prospects in contaminated water treatment. (C) 2016 Elsevier Inc. All rights reserved.