A room-temperature electrocatalytic process that effects the overall chemical reaction CO₂ + 2H₂O → CH₄ + 2O₂ has been investigated as a means of removing carbon dioxide from air and restoring oxygen to the air. The process was originally intended for use in a spacecraft life-support system, in which the methane would be vented to outer space. The process may also have potential utility in terrestrial applications in which either or both of the methane and oxygen produced might be utilized or vented to the atmosphere.