The need to minimize the amount of CO2 in the atmosphere is greater and greater and consequently sequestration of industrial emissions in adequate geologic formations is a present-day necessity. As is known, CO2 cannot be injected anywhere in the subsurface, but geological formations with the appropriate requisites must be identified. This requires accurate investigations by means of a detailed characterisation of the rocks that make up the possible reservoirs in order to build a reliable model whose CO2 storage capacity can be planned in advance and guarantee an efficient use of the reservoir. This study presents the characterization of a geological formation made up of carbonate rocks (“Miliolitico” Formation Auct.) located at the base of the Eocene stratigraphic sequence in South-Western Sardinia (Sulcis Basin) that we believe can be used as a natural reservoir for CO2 storage in a very important mining district, the Sulcis Coal Basin (SW Sardinia). In Italy, the Sulcis Coal Basin represents one of the few, if not the only, carbon reserve with an important mining potential. The Basin is characterised by a significant presence both of minable coal, and of deep carbon layers that could also be suitable for the implementation of CBM-ECBM (Coal Bed Methane – Enhanced Coal Bed Methane) production techniques.