The present invention relates to a gas generator for a motor vehicle safety device. The generator includes at least a combustion chamber and a gas tank. The combustion chamber contains a pyrotechnic initiator and pyrotechnic charge for generating gas and including at least one oxidizing material. Combustion of the charge is triggered by the initiator. The gas tank is closed towards the combustion chamber by a capsule. The capsule is suitable for giving way during combustion of the charge in order to release the gas from the tank and exhaust it towards the outside. The combustion chamber contains a metal charge of at least one metal. The metal charge is distinct from the pyrotechnic charge.