The invention relates to a combustion chamber assembly for an airbag module of a motor vehicle, having a combustion chamber housing, which encloses a combustion chamber, and having a housing receptacle, in which the combustion chamber housing is to be disposed such that the combustion chamber housing with the outer surface thereof is running along an inner surface of the housing receptacle, exit areas being provided in each case in the combustion chamber housing and the housing receptacle, said areas upon proper configuration of the combustion chamber housing in the housing receptacle being spatially associated with one another such that gas generated in the combustion chamber may exit through the exit areas of the combustion chamber housing and the housing receptacle into the surroundings. According to the invention, at least one shaped region (15, 25) is implemented on the combustion chamber housing (10) and/or on the housing receptacle (2) such that an expansion chamber (E) is defined in the area of the shaped region (15, 25) between the outer surface (12) of the combustion chamber housing (10) and the inner surface (22) of the housing receptacle (2), the expansion chamber being at least partially filled with the material of a section (14) by deformation of said section (14) of the combustion chamber housing (10) upon proper positioning of the combustion chamber housing (10) in the housing receptacle (2).