Geological sequestration of CO2 is an immediately available and technologically feasible means of reducing CO2 emissions into the atmosphere, which is particularly suited to landlocked sedimentary basins. Geoscience, engineering, economic and public issues need addressing by governments and industry before proceeding with full scale implementation. Specific site selection should be based on a suitability analysis, a proper inventory of potential sites, an assessment of the fate of the injected CO2 and a capacity determination, together with surface criteria such as CO2 capture and transport. The suitability analysis, both at the basin and regional scales, is based on geological, geothermal, hydrodynamic, basin maturity, economic and societal criteria. The inventory of sequestration sites needs also identification of major CO2 point sources and a cost benefit analysis. The potential for CO2 escape and migration is a deciding factor in screening out unsafe sites. Site capacity should be determined based on in situ conditions and CO2 properties and behavior. Transforming the geological space into the CO2 space is an important step along the road map for selection of suitable CO2 injection sites that allows the identification of safe large capacity sites. An example of application from the Alberta basin is presented.