The cover picture depicts not only the internationality of the polyoxometalate community, well-reflected at the International Polyoxometalate Symposium (Jacobs University, Bremen July 28–August 1, 2009) on which this cluster issue is based, but also the huge scope of these compounds. The diversity of aspects in this issue is highlighted on the cover by a selection of graphics placed over the country of origin of the authors. Structural features (M. T. Pope et al.), mechanisms of formation (J. Poblet et al.), homogeneous oxidation catalysis (O. Kholdeeva et al.), design of enantioselective catalysts (M. Bonchio et al.) and photochemistry based analytical techniques (T. Yamase et al.) are some of the topics you will find. Mr Rami Al-Oweini (Jacobs University) is thanked for his creative design.