The present structure determination of di-mu-hydroxo-bis{[N,N'-bis(dipiperidinomethylene)propane-1,3-diamine-kappa(2)N,N']copper(II)} bis(hexafluorophosphate), [Cu(2)(OH)(2)(C(25)H(46)N(6))(2)](PF(6))(2), is the first to crystallographically characterize a Cu(2)(mu-OH)(2) complex with a bidentate guanidine ligand. The cation lies on a crystallographic inversion centre and shows planar fourfold coordination of the copper centres. The Cu(2)(mu-OH)(2) species can be distinguished from Cu(2)(mu-O)(2) by the Cu-O bond lengths. The packing is determined by strong intermolecular anion-cation hydrogen bonds.