Abstract: A gas generator construction particularly for the inflation of inflatable protective bags which are used in safety systems of vehicles comprises a housing with a central tubular housing part which contains an ignition device that is surrounded by a reaction chamber containing a gas generating charge which in turn is surrounded by an outer filter housing. The gases which are generated in the reaction chamber are directed through openings and into the filter housing and then outwardly through slots of the filter housing for use in expanding the protective bag. The reaction chamber and the filter chamber are formed by an annular substantially S-shaped wall member which has a bottom forming wall portion for the reaction chamber which is joined to the central tubular part, for example, by welding.