Introduction: It has been recognized since 1970 that carbon dioxide clathrate hydrate is thermodynamically stable at the Martian poles (at least seasonally), in the interiors of both polar caps, and perhaps more widely [19]. Other nonpolar gases could form hydrates on Mars, including noble gases, nitrogen, sulfur dioxide, and methane [6,8,9]. We reexamine the possible global CO2 inventory of Mars, the magnitude of possible regional outgassing events, possible mechanisms of formation of clathrates, and the stability of clathrate hydrates. Dissociation of clathrate hydrates may be an important link in the catastrophic formation of chaotic terrain, outflow channels, and northern plains deposits, and clathrates may influence the dynamic behavior of Martian polar caps and ice flows in the fretted canyons.