Method and apparatus for sterilizing articles

Method and apparatus for sterilizing articles including introducing the article and liquid solution into a collapsible pouch formed of vapor-impermeable sheet material, sealing the collapsible pouch to form a gas-tight assembly, and heating the gas-tight assembly to vaporize the liquid solution to produce an atmosphere of hot vapor. The liquid is introduced into the pouch in a quantity sufficient to create an overpressure when vaporized which is indicated by the collapsible pouch expanding to a distended condition. In one embodiment, the liquid solution is vaporized by irradiating the gas-tight assembly with microwave radiation. In other embodiments particularly suited for sterilizing a plurality of metallic articles, the at least one article is surrounded by shielding, which may be separate from or integrated with the pouch, which presents a barrier to the transmission of microwave radiation. The pouch containing the shielded article or articles and liquid solution is sealed and the gas-tight assembly is irradiated with microwave radiation to vaporize the liquid whereupon the article or articles are sterilized under the effect of vapor under pressure.