Heterocyclic compounds with silicon and metal represent an exciting family of inorganic compounds for a variety of reasons as, exceptionally high chemo-, regio- and stereoselectivity of formation from monosiloxanolate and monometallic units, relevance to (supposed) structural features of silica-supported catalysts, unusual structural features as μ4-square planar O2- or μ6hexagonal planar Cl- ligands, interesting magnetic properties as well as catalytic applications. The present work presents the synthesis and characterization of some new cyclosiloxanolate cage (cluster) complexes of transition metals (Fig. 1) . Fig.1. Cyclosiloxanolate cage (cluster) complexes of metals The structures were determined by spectral (FTIR, XRF and NMR) methods, and elemental analysis. The thermal stability was evaluated by thermogravimetrical analysis. The moisture stability of the heterocyclic compounds was evaluated by water vapor sorption analysis in dynamic regime. Sorption-desorption isotherms were registered at three temperatures.