Bis(2-aminopyrimidine-N)diaquabis(saccharinato-O)copper(II) di(2-aminopyrimidine), [Cu(sac-O)2(ampym-N)2(H 2O)2]·2ampym was synthesized and characterized by means of elemental analysis, IR and UV-vis spectroscopy, magnetic susceptibility, simultaneous TG, DTG, DTA techniques, and X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c [a = 7.4697(5), b = 10.1679(5), c = 22.743(2) Å, β = 92.844(5), Z = 2, R = 0.0275, wR = 0.0757, V = 1725.26(19) Å3]. The copper atom is bonded to two ampym N atoms and two sac O atoms as well as to two water O atoms in trans positions in the geometry of a distorted octahedron. There are also two ampym moieties as solvate molecules in the unit cell. The crystal structure is stabilized by N-H⋯O, O-H⋯N and C-H⋯O type hydrogen bonding interactions. Intermolecular π-π interactions between the phenyl rings of ampym groups and C-H⋯π interactions also support the packing of the molecules. The thermal decomposition of the complex has been studied. © 2006 Verlag der Zeitschrift für Naturforschung.