Gas uptake tests were performed with a high pressure cell which was equipped with a mechanical stirrer to convert the most part of solution to hydrate. The cell inner volume including tubing was determined to be 113.0 cm 3 . About 30 g of aqueous solutions were subjected to the tests. Gas uptake by the hydrate was calculated by density differences between before and after hydrate formation. Density of the gas was calculated with the experimental pressure and temperature conditions by REFPROP 10