Dissolution rate of a liquid CO 2 droplet in the pressurized water flow has been experimentally measured for both cases with and without clathrate on the surface, and various effects of flow velocity, temperature and pressure on the dissolution rate have been clarified. Based on the results, shrinking or dissolution mechanism of CO 2 droplet covered with clathrate film has been discussed in detail. Further, the dissolution behavior of liquid CO 2 droplets dispersed into the sea water has been numerically simulated using measured dissolution rates.