This invention provides a pressurized cooker comprising a vessel and a lid, characterized in that said lid is provided with an opening and means are provided for fitting a resilient plate made of a material such as rubber over the said opening, said means for fitting the said plate comprises a cap capable of being applied against the said plate towards the periphery of the latter on to the edges of said opening on the cooker, the base of the said cap is provided with an opening or is positioned spaced from the said plate with means provided for the space between the cap and the plate to communicate with the interior of the cooker when the cap is fitted internally or with the exterior when the cap is fitted externally. See Fig.I.