Abstract: A pressure cooker has a vent opening in its cover in which a sealing plug rises in response to pressure developed in the cooker and the cover handle has a slidably mounted lock member which is manually movable into an "open" position when its abutment portion overlies the vent opening to prevent rise of the plug and thereby development of pressure within the cooker. The lock member can be moved out of said "open" position into a "cook" position where its abutment portion is clear of the vent opening and the plug is free to rise and seal the vent opening to permit pressure development within the cooker. The lock member, however, has a catch portion which, in the cook position of the lock member, catches with a cooker body handle so that the cover cannot be rotated relative to the cooker body, as is required to remove the cover from the cooker.