The reaction of copper(II) nitrate trihydrate and 2-(2-pyridyl)benzimidazole (pybzim) leads to [Cu(pybzim) 2 (NO 3 )](NO 3 ). The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structure of the [Cu(pybzim) 2 (NO 3 )] + cation has been calculated with the density functional theory (DFT) method. The spin-allowed doublet–doublet electronic transitions of [Cu(pybzim) 2 (NO 3 )] + have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.