Two organic-inorganic hybrid polyoxometalates, consist of 1-butyl-3-methylimidazolium salts of (W10O32)(4-) and (RW12O40)(3-) polyanions were prepared and characterized by thermal analysis, X-ray diffraction, FT-IR, diffuse reflectance UV-Vis spectroscopic methods and nitrogen absorption-desorption determination (BET). These heterogeneous catalysts were used for synthesis of azlactones by the reaction of aldehydes with hippuric acid and acetic anhydride under solvent-free conditions. These catalysts were reused several times without loss of their activities. (C) 2011 Elsevier B.V. All rights reserved.