Abstract: A propellant module assembly is adapted for containing a liquid propellant which is used to inflate a vehicular air bag. The module assembly includes an igniter; a liquid propellant; a propellant and igniter capsule; and a rupturable closure member. The capsule and rupturable member are compatible with, and will not deteriorate as a result of contact with the liquid propellant. The liquid propellant, when ignited, will not produce toxic gases, and will not subject vehicle occupants to the possibility of chemical burns, as can occur with solid propellants.