The novel catalyst system (NH4)(8)Mo10O34 Was found to be active for transesterification between dimethyl carbonate and phenol based on the comparisons of performance over Sn-, Pb- and Mo-based metal complexes. X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), the temperature-programmed desorption (TPD) with mass spectroscopy, thermogravimetic analysis (TGA), Infrared spectroscopy (FT-IR). and Raman spectroscopy were conducted to characterize the catalysts. (NH4)(8)Mo10O34 can be formed from (NH4)(G)Mo7O24 center dot 4H(2)O through calcinations at similar to 423 K. The Mo species dissolved from (NH4)(8)Mo10O34 appeared to play the main part in this reaction. This homogeneous catalyst showed the superior turnover frequency to those of the homogeneous lead complexes obtained from PbO. The activation energy was determined to be 87.1 kJ mol(-1). (C) 2009 Elsevier B.V. All rights reserved.