The cobalamin is a vitamin with a key role in the normal functioning of the brain and nervous system, and the formation of red blood cells. Cobalamin contains a diamagnetic Co (III) ion and its role is well known in the biochemistry of this systems. In order to explore the biomimetic compounds of the cobalamine (B12) coenzymes, the coordination chemistry of cobalt (II, III) is analyzed [1, 2]. In this study, we present the single-crystal X-ray structure of neutral cobalt (III) complex with 2,3-pyridinedicarboxylate ligand. The violet complex, [Co (2,3-pydcH)3]3H2O, was synthesized by reaction of Co(II) salt with 2,3-pyridinedicarboxylic acid in the presence of K2S2O8 . The mononuclear complex crystallizes as plate, in the monoclinic space group P21/c, having the lattice parameters: a=1.566(2) Å; b=0.7639(10)Å, c= 2.159(3) Å, =110.50(4)o, V=2409Å3, Z=4. The cobalt (III) ion exhibits a distorted octahedral geometry with a [N3O3] chromophore. Each ligand coordinates in a bidentate, chelate mode through the pyridine nitrogen atom and oxygen atom of the mono deprotonated 2-carboxylic groups. (Fig.1.a) The longest axe is formed by two Co-N bonds with the lenghts 1.914 Å and 1.952 Å, since on the other two axes we have 3 Co-O bonds (1.884 Å, 1.887 Å, 1.905 Å) and one Co-N bond (1.913 Å). The crystal packing reveal - stacking interactions between the pyridine rings of the ligand belonging to neighbor complex units, as well as an extended hydrogen bond network formed by the water molecules and non coordinated carboxylic groups. (Fig.1.b)