Wu in his Review on pages 1591–1608 describes the power of multi-wavelength Raman spectroscopy in studying heterogeneous catalysts. Two supported vanadia catalyst systems, VOx/SiO2 and VOx/CeO2, are utilized as examples to showcase how one can employ this Raman technique to investigate the heterogeneous structure of active oxide clusters and to understand the complex interaction between the oxide clusters and the support. The qualitative and quantitative structural information gained from the multi-wavelength Raman spectroscopy investigations would help to provide fundamental insights for designing more efficient supported metal oxide catalysts.