A new experimental technique is being developed to measure the solubility of gases and vapors in polymers or other sorbents at elevated temperatures and pressures. This technique involves measuring the total weight of a pressurized vessel containing a sorbent material pressurized with a vapor, assessing the amount of vapor in the headspace via an equation of state, and evaluating the total amount of vapor within the polymer phase based on the difference. Results are presented for the measurement of capsule volumes by weighing empty cells containing a gas of known density. Sorption isotherms for carbon dioxide and nitrogen on Calgon PSC Carbon were measured using this method. In addition, the static sorption capsule was used to measure the solubility of carbon dioxide in polyvinyl acetate. These results compare well with literature data.