Geologic storage of CO (sub 2) in ocean basalt reservoirs is a potentially long-term solution to offset anthropogenic greenhouse gas emissions. Prior drilling at Deep Sea Drilling Project (DSDP)/Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) Sites 1256 and 504 provides evidence that the extrusive ocean crust has sufficient porosity and permeability to enable storage of large volumes of CO (sub 2) . Six intervals are identified as potential reservoirs in the shallow crust at Sites 1256 and 504, with new and reprocessed estimates of porosity from electrical resistivity logs ranging from 6% to 14% and permeability from approximately 10 (super -14) to 10 (super -15) m (super 2) . Calculations using specific reservoir thickness and porosity estimates suggest that even the smallest reservoir could provide storage capacity for decades of global anthropogenic carbon emissions. In situ hydrologic experiments and pilot injection studies are needed to confirm high permeability and porosity estimates at Sites 1256 and 504, as well as the potential for CO (sub 2) injection and retention in these basalt reservoirs.