A new kind of polyoxometalate (POM) ionic liquid ([(CH3)(3)NCH2CH2OH](5)PV2Mo10O40) (abbreviated as Ch(5)PMo(10)V(2)O(40)) has been synthesized by a precipitation/ion exchange method with choline chloride and H5PMo10V2O40 as precursors. The produced salt turned out to be an original ionic liquid (IL) catalyst and exhibited a novel switchable property based on temperature variation. In this regard, it refers to a thermoregulated feature that elevated temperature leads to the miscibility of catalyst and substrate. As decreasing the temperature, the catalyst precipitates and becomes heterogeneous form to be separated automatically from the reaction mixture. The combination of POMs with choline chloride was also proved to be effective in catalyzing the oxidation of starch, which showed higher or nearly identical performance with traditional catalysts, such as FeSO4. Results demonstrated the catalyst was easily separated from the products and the retrieved Ch(5)PMo(10)V(2)O(40) could be repeatedly used without appreciable loss of its performance, which highlighted the practical application of this important biomass. (C) 2013 Elsevier B.V. All rights reserved.