The polymeric title compounds, namely catena-poly[[[di-mu-but-2-enoato-kappa(3)O:O,O';kappa(3)O,O':O'-bis[diaquadibut-2-enoato-kappaO;kappa(2)O,O'-neodymium(III)]]-mu-4,4'-bipyridyl N,N'-dioxide-kappa(2)O:O'] 4,4'-bipyridyl N,N'-dioxide solvate] and the erbium(III) and yttrium(III) analogues, {[Ln(2)(C(4)H(5)O(2))(6)(C(10)H(8)N(2)O(2))(H(2)O)(4)].C(10)H(8)N(2)O(2)}(n) (Ln = Nd, Er and Y), form from [Ln(2)(bt)(6)(H(2)O)(4)] dimers (bt is but-2-enoate) bridged by 4,4'-bipyridyl dioxide (bno) spacers into sets of parallel chains; these linear arrays are interconnected by aqua-mediated hydrogen bonds into broad two-dimensional structures, which in turn interact with each other though the hydrogen-bonded bridged bno solvent units. Both independent bno units in the structures are bisected by symmetry centres.