Dissolution of CO2 droplets in the ocean has been studied. Owing to hydrogen bonding and supersaturation with CO2, seawater at the surface of the CO2 droplets becomes highly structured. Since this quasi-crystalline structure is similar to that of hydrate crystal elements, hydrate formation on the droplets will not cause a dramatic decrease in the dissolution rate as reported in the literature. Mass transfer of a buoyant CO2 droplet in Stokes flow in the ocean is analysed. Based on the derived mass-transfer coefficients, shrinkage rates for CO2 droplets without and with a hydrate shell are predicted. Good agreement is observed between predictions and experimental data.