The title compound {[Cu₂Ho₂(C₄H₅O₂)₁₀(H₂O)₄]·3H₂O}_n, is a one-dimensional 3d/4f organic-inorganic hybrid complex, the Ho^III member of the isotypic lanthanoid series with Ln = Gd^III, Er^III and Y^III. The structure shows an alternation of Cu₂ and Ho₂ dinuclear units bridged by the ligands and hydrogen bonds only. The chains are composed of Cu₂ classical dinuclear η¹:η¹:μ₂ fourfold bridges [Cu⋯Cu = 2.6417 (9) Å] and of Ho₂ units bridged by two η²:η¹:μ₂ carboxylate units. This results in distorted square-based pyramidal CuO₅ units and irregular HoO₉ units. The alternating Cu₂ and Ho₂ units are bridged into linear arrays along the a axis by a set of one η²:η¹:μ₂ carboxylate O atom and two hydrogen bonds with Cu⋯Ho separations of 4.4883 (10) and 4.5086 (10) Å. The distance between adjacent chains, as calculated by the closest and furthest distances between two chains, covers the range 10-14 Å. The H atoms of the water molecules could not be located, but the O⋯O separations for these species suggest the presence of O–H⋯O hydrogen bonds.