Carbon capture and storage (CCS) has been described as an indispensable element in fighting dangerous climate change. At the same time, the technology is associated with significant uncertainties and risks. Focusing on the geological storage of captured CO2, this article takes stock of ongoing processes for accommodating CCS in international law. It finds that the current approach to CCS is patchy and, partly, short on substance. It then attempts to establish to what extent a harmonized international approach to regulating CCS is called for and how it may be achieved.