The electronic structure of [Co(ntb)(nic)(+) complex ion are optimized by using density functional theory (DFT) method with mix basis set. Where (ntb) represents tris(2-benzimidazolylmethyl)amine ligand and (nic) is the anion of nicotinic acids. Six different fields, vacuum, chloroform, butanonitrile, methanol, water and formamide solvents are used in these calculations. The calculated structural parameters indicate that (nic) ligand coordinates to cobalt(II) containing (ntb) ligand with one oxygen atom in butanonitrile, methanol, water and formamide solvents but coordinates with two oxygen atoms in vacuum. These results are supported with IR, UV and H-1 NMR spectra. According to the calculated results, the geometry of [Co(ntb)(nic)](+) complex ion is distorted octahedral in vacuum while the geometry is distorted square pyramidal in the all other solvents. Distorted octahedral [Co(ntb)(nic)(+) complex ion have not been synthesized as experimentally and it is predicted with computational chemistry methods. (C) 2014 Elsevier B.V. All rights reserved.