Abstract: A gas generator, such as for a safety device in vehicles, comprises a pressure chamber which is filled with compressed gas and which is closed off from an environment of the gas generator by a membrane. The compressed gas contains a gaseous oxidant which is composed predominantly of oxygen. The pressure chamber receives a solid fuel, wherein the compressed gas is in direct contact with the fuel before the gas generator is activated. When the gas generator is activated, an igniter separated pressure-tightly from the pressure chamber triggers a conversion of the gaseous oxidant with the solid fuel, with heat being generated. The fuel is in the form of a gas-permeable fuel body made up of one or more fibers, and the molar fraction of the gaseous oxidant in the compressed gas is at least 1.1 times the amount of oxidant required for a stoichiometric conversion of the gas-permeable fuel body. A module and a vehicle safety system comprise such a gas generator.