The crystal structure of bis(tetra-n-butylammonium)bis(μ 2 -hydroxo)-bis(1,2,3,4-tetrakis(methoxycarbonyl)-1,3-butadiene-1,4-diyl)-di-palladium, [NBu 4 ] 2 [Pd 2 {C 4 (COOMe) 4 } 2 (μ-OH) 2 ], was determined ab initio by X-ray single-crystal diffractometry using the charge flipping method. The compound crystallizes in the monoclinic system with P2 1 /c as space group and the following cell parameters: a=12.8481(6)Å, b=63.744(3)Å, c=16.6102(8)Å, β=111.943(10). The asymmetric unit is formed by two molecules, and the unit cell contains eight molecules (Z=8) giving a density of 1.369gcm −3 . The coordination around the Pd(II) atoms is approximately planar, the methoxycarbonyl groups at the α and β positions relative to Pd are perpendicular and parallel to the palladacycle ring, respectively, and the {Pd(μ-O)} 2 core has a bent conformation. The structure closely resembles the features reported previously for other palladacyclopentadiene complexes.