Abstract: A latching mechanism and pressure-operated safety lock for a pressure vessel such as a pressure fryer, the invention positively locks a lid of a pressure fryer over the cooking pot by means of a latch mounted on the distal end of a bar which centrally engages the lid to bias the lid into a pressure-tight relation with upper peripheral edges of the pot. The latch includes a spindle having a hook element formed at the lower end for engaging a catch mounted on the body of the fryer on tightening of the latch by rotation of a hub mounted on the spindle. The hub is provided with radially extending handles which facilitate rotation thereof. A safety lock operated by pressure generated by food cooking within the fryer cooperates with the latch to prevent opening of the lid when pressure of at least a predetermined value exists within the fryer.