Six new hybrid compounds based on polyoxometalates and transition metal complexes, [SiW₁₂O₄₀][Ag₄(2,2′-bpy)₄(4,4′-bpy)₃]·2H₂O (1), [SiMo₁₂O₄₀][Cu(2,2′-bpy)(H4,4′-bpy)₂(H₂O)][H4,4-bpy] (2), [PMo₁₂V₂O₄₂][Cd₂(Phen)₂(4,4′-bpy)₂(H₂O)₂(C₂O₄)]·2H₂O (3), [PMo₁₂V₂O₄₂][Cu₂(4,4′-bpy)₂][Cu₂(Phen)(4,4′-bpy)₂]·3H₂O (4), [SiMo₁₂V₂O₄₂][Cu₂(Phen)₂(4,4′-bpy)]₂ (5) and [GeMo₁₂V₂O₄₂][Cu₂(Phen)₂(4,4′-bpy)]₂ (6) (bpy = bipyridine, Phen = phenanthroline), have been synthesized and characterized. Compound 1 contains a discrete tetranuclear silver-2,2′-bpy-4,4′-bpy complex; compound 2 is the first example where the polyoxometalate supports a metal–aqua–2,2′-bpy-4,4′-bpy complex; it should be noted that the complex contains a 2,2′-bpy and two 4,4′-bpy ligands; compound 3 is the first hybrid compound based on polyoxometalates and metal–aqua–4,4′-bpy–oxalic–phenanthroline complexes; and compound 4 is a novel hybrid compound based on polyoxometalates, extended metal–4,4′-bpy complexes and extended metal–4,4′-bpy–phenanthroline complexes together. Compounds 5 and 6 are isomorphous and isostructural; both exhibit a supramolecular structure constructed from bicapped Keggin POMs and metal–4,4′-bpy–phenanthroline complexes.