Applying first principles Born-Oppenheimer Molecular Dynamics and Grand Canonical Monte Carlo simulations, we investigated three prototype Zeolite Imidazolate Frameworks to assess the role of their electronic and structural details on CO2 adsorption. We found that the regions proximal to the linkers are the preferential adsorption sites of CO2. The uptake capacity at low pressures is related to the electrostatic interaction of the adsorbate with the crystal. At higher pressures, CO2 adsorption depends linearly on the surface areas and porosities of ZIFs. (C) 2013 Elsevier B.V. All rights reserved.