Chemistry of macrocyclic hosts cucurbit[n]urils is a new field of supramolecular chemistry. Cucurbit[n]urils (CB[n]) (C6nH6nN4nO2n, n = 5 – 8) are rigid barrel-shaped molecules with two hydrophilic carbonyl-fringed portals and open hydrophobic inner cavity. These remarkable structural features lead to rich variety of compounds, based on CB[n] cavitands and metal complexes, which may be classified into several types: 1) Supramolecular adducts of CB[n] with mono- and poly-nuclear metal aqua complexes, based on H-bonds between aqua ligands and carbonyl groups of CB[n]; 2) Metal complexes with CB[n] as the first coordination sphere ligand; 3) Inclusion compounds of metal complexes into the cavity of CB[n]. We have obtained in crystalline state and structurally characterized a wide range of compounds, belonging to all these types.figureThree approaches for synthesis of CB[8] inclusion compounds were developed: 1) “metal aqua-complex + ligand@CB[8]”; 2) direct reaction “host + guest”; 3) “guest substitution” approach.figureThese methods were proved to be successful for isolation with high yield of CB[8] inclusion compounds with transition metal complexes as guests, containing aliphatic polyamines en, dien and cyclam as ligands. The resulting products were fully characterized both in solid state and in aqueous solution by X-ray single crystal analysis, ESI-MS, IR, UV, 1H NMR and ESR-spectroscopy. In addition, reactivity of encapsulated guests towards oxidation, isomerization and thermolysis was investigated in comparison with those of free metal complexes. It has been shown, that inclusion into the cavity of cucurbit[8]uril may be helpful for: 1) isolation of metal complexes with unusual oxidation states and coordination environments; 2) stabilization of guest complexes in solid state and in solution towards thermolysis, isomerization reaction etc.