Hydrogen and carbon monoxide are supersaturated in marine surface waters compared to the atmosphere, providing an accessible energy source for microbial communities. While marine CO oxidation is well-described, it is not yet known whether marine bacteria can also consume H2. We integrated genome-resolved metagenomics, biogeochemistry, thermodynamic modelling and culture-based analyses to profile H2 and CO oxidation by marine bacteria, to determine whether H2 is a significant energy source for marine communities.