blue slender crystals of [Cu(C~1~2H~8N~2)(H~2O)(C~4H~4O~4)]·2H~2O were obtained from the solution of CuCl~2, 1,10-phenanthroline, succinic acid and NaOH in CH~3OH/H~2O solution. The crystal structure was determined by single crystal X-ray diffraction. The title complex crystallized in the triclinic space group P1(No.2) with a=0.7462(1) nm, b=(0.9959)1 nm, c=1.2266(1) nm, α=75.02(1)°, β=82.38(1)°,γ =74.76(1)°, V=0.8475(2) nm^3, Z=2, D~c=1.622 g·cm^3, F(000)=426, R=0. 0450, wR^2=0.0951 for 2789 observed reflections F~0^2≥2σ(F~0^2) out of 3882 unique reflections. The crystal structure consists of supramolecular double chains ^1~∞[Cu(phen)~2(H~2O)·(C~4H~4O~4) ~2~/~2]~2 and water molecules, in which each Cu atom is square- pyramidally coordinated by two N atoms of one chelating phen ligand, two O atoms of different bidentate bridging C~4H~4O~4^2^- ligands and one O atom of water molecule with one carboxyl O atom at the apical position [d(Cu－N)=0.2006(3), 0.2032(3)nm; basal d(Cu－O)=0. 1972(2), 0.1973(2)nm; axial d(Cu－O)=0.2210(2)nm]. The twisted C~4H~4O~4^2^- ligands interlink square-pyramidally coordinated Cu atoms to form supramolecular chain ^1~∞[Cu(phen)~2(H~2O)·(C~4H~4O~4) ~2~/~2]~2 with phen ligands extended outwards on one side to form pitches.

Key words: COPPER COMPLEX, CRYSTAL STRUCTURE, PHENANTHROLINE, BUTANEDIOIC ACID, SUPERMOLECULAR STRUCTURE