Abstract. Triclinic single crystals of Cu4(H3N-(CH2)9-NH3)(OH)2[C6H2(COO)4]2*5H2O have been prepared in aqueous solution at 80 °C in the presence of 1,9-diaminononane. Space group P-1 (no. 2) with a = 1057.5(2), b = 1166.0(2), c = 1576.7(2) pm, alpha = 106.080(10)°, beta = 90.73(2)° and gamma = 94.050(10)°. The four crystallographic independent Cu2+ ions are surrounded by five oxygen atoms each with Cu−O distances between 191.4(3) and 231.7(4) pm. The connection between the Cu2+ coordination polyhedra and the [C6H2(COO)4]4- anions leads to a three-dimensional framework with negative excess charge and wide centrosymmetric channel-like voids.These voids extend parallel to [001] with the diagonal of the nearly rectangular crossection of approximately 900 pm. The channels of the framework accommodate [H3N-(CH2)9-NH3]2+-cations and water molecules, which are not connected to Cu2+. The nonane-1,9-diammonium-cations adopt a partial gauche conformation. Thermoanalytical measurements in air show a loss of water of crystallization starting at 90 °C and finishing at approx. 170 °C. The dehydrated compound is stable up to 260 °C followed by an exothermic decomposition yielding copper oxide.