A sealable decontamination holding vessel configured to isolate contaminated items being held therein until safe opening of the vessel occurs during a high pressure and temperature sterilization cycle in an autoclave. The vessel basically includes an outer container, a perforated inner receptacle, containment bag and cover lid. The inner receptacle fits into the outer container. The containment bag fits within the inner receptacle with an open end of the bag draped over an open top lip of the inner receptacle. The cover lid is secured and sealed over the open top of the outer container. Patches of self-adhering sealing materials are placed over vent holes in the outer container and cover lid so as to seal the same until they unseal in response to contact with sterilizing steam in the autoclave allowing flow of the steam through the outer container into the inner receptacle and containment bag.