The compounds M[VO(O-2)(2)bpy]center dot nH(2)O (M = Li+-Rb+) and Cs[VO(O-2)(2)bPY]center dot H2O2 were characterized by thermogravimetry (TG). In the course of TG experiments, performed from 25 up to 550 degrees C, three main stages of decomposition were observed: (i) dehydration, (ii) releasing of the oxygen molecules and (iii) decomposition of bpy. The final product of decomposition is MVO3, with small amounts of paramagnetic vanadium(IV) species. Volatile products were detected on-line using mass spectrometer. Mechanism of the decomposition is discussed on the basis of crystal structures of complexes. The main role is played by hydrogen bonds involving peroxo ligands and polarising power of alkali metal ions. (c) 2010 Elsevier B.V. All rights reserved.