Density functional theory calculations were carried out with a stable seven atom pentagonal bipyramidal copper cluster acting as a biomimetic CO2 hydration catalyst exhibiting carbonic anhydrase-like mechanism. The cluster was found to be active for catalyzing the reaction resulting in the formation of bicarbonate ions and protons. The reaction pathway was found to be identical to that of the alpha-carbonic anhydrase action involving water adsorption and deprotonation, CO2 interaction and proton transfer, and water attack and HCO3- displacement steps. The calculations were carried out both in vacuum and in water as the solvent. No significant differences in the energetics of the elementary steps were observed in vacuum and in solvated state indicating the feasibility of the use of Cu-7 as the active species in industrial gas-phase CO2 capture systems. (C) 2015 Elsevier Ltd. All rights reserved.