An airbag inflator (10) with venturi effect cooling and gas supplement. The inflator includes a housing (14) having a quantity of gas-producing fuel (26) therein, and possibly a stored gas also, along with appropriate igniters (32). These materials are stored within a gas production chamber (24) of the housing. The gas leaving this chamber travels through the housing to an exit port (52) on the housing. Intermediate the gas production chamber and the housing exit port is a venturi section (38) of the housing. This section reduces the pressure of the gas, and thus the pressure at the interior end of draw vents (46) opening onto the venturi section. The vents therefore draw outside air into the housing to mix with the gas. This cools the gas to the desired temperature, and also supplements the gas exiting the housing. As such, the need for a heat sink to cool the gas is reduced or eliminated. Furthermore, since the cushion is inflated with a mixture of gas and air, the amount of gas typically needed is reduced by the amount of added air. This permits the amount of fuel to be reduced, thus reducing cost and weight.