The asymmetric unit of the title compound, [{Sn(C 4 H 9 ) 2 (C 6 H 5 COO)} 2 O] 2 , consists of two half molecules, completed by application of inversion symmetry. Both molecules adopt a ladder structure typical for this class of dimeric tetraorganodistannoxane dicarboxylates characterized by a centrosymmetric four-membered (Sn—O) 2 ring of rhomboidal shape that is extended on both sides by folded six-membered Sn—O—C rings. To a first approximation, both kinds of Sn atoms (Sn i and Sn o ) are trigonal–bipyramidally coordinated. The bond angles between the n -butyl groups are widened [135.64 (7)–146.20 (7)°] in comparison with an ideal trigonal bipyramid. Sn—O bond lengths within the { R 2 SnO 3 } coordination sphere depend strongly on the position of the corresponding O atom – axial ( ax ) or equatorial ( eq ) – as well as on the functionality of the carboxylate groups which exhibit μ 2 (–COO i ) and μ 1 (–COO o ) coordination modes, respectively. In summary, the following sequence of distances [mean values] is found: d (Sn o —Oμ 3 ) eq [2.024 (2) Å] < d (Sn i —Oμ 3 ) eq [2.044 (2) Å] < d (Sn i —Oμ 3 ) ax [2.158 (6) Å] < d (Sn o —Oμ 1 -carb) ax [2.182 (6) Å] < d (Sn i —Oμ 2 -carb) ax [2.250 (2) Å] ≃ d (Sn o —O μ 2 -carb ) ax [2.247 (12) Å]. The n -butyl groups adopt an anti–anti conformation with exception of two disordered outer n -butyl groups of the second molecule which exhibit gauche–anti and anti–gauche conformations. Weak intramolecular Sn...O interactions between the different O atoms of the outer carboxyl groups with the inner, as well as outer, Sn atoms give rise to a strongly distorted octahedral coordination at these Sn atoms. Intermolecular interactions between the individual molecules are restricted to van der Waals and O...H—C interactions of which a nearly linear very short C—H...O contact between the H atom of the phenyl group of one of the molecules with the outer non-coordinating C=O group of the other molecule is the most prominent. It gives rise to a chain-like arrangement of the molecules along [111]. The two n -butyl groups attached to the outer Sn atom of one molecule are disordered over two sets of sites with occupancies of 0.806 (3)/0.194 (3) and 0.702 (3)/0.298 (3).