Data needed for evaluation of ocean CO2-sequestering technologies include the solubility of CO2 and density of CO2 hydrate at 30 MPa. Theses were measured using a high-pressure facility suitable for simulating pressure and temperature conditions 3000 m beneath the ocean surface. The solubility decreases linearly with decreasing water temperature, which is opposite to the temperature dependence in the non-hydrate region. The measured solubility agrees with the published value for the non-hydrate region at an equilibrium temperature of 12 degrees C. The hydrate density was estimated from pressure drop, temperature increase, and concentration changes, followed by precipitation of CO2 hydrate. The estimated CO2 hydrate density varies from 1.11 to 1.09, depending on the fraction of CO2 in hydrate form.