Abstract: A liquefied gas system for capturing boil-off gas and reversibly adsorbing the boil-off gas on an adsorbent for later desorption and use comprises a first vessel for storing liquefied gas; a means for delivering gas from the first vessel to a system endpoint; a second vessel for storing boil-off gas emitted from the first vessel, the second vessel containing at least one adsorbent; a means for delivering boil-off gas from the first vessel to the second vessel, whereby the boil-off gas is reversibly stored on the at least one adsorbent; and a means for delivering the stored boil-off gas from the second vessel to the system endpoint. Also disclosed is a method of capturing boil-off gas from a liquefied gas system, wherein the captured boil-off gas is captured on an adsorbent for further use in the system. In one embodiment of the system and the method, the liquefied gas is liquid hydrogen, and the captured boil-off gas is used to power a hydrogen fuel cell.