Abstract: A sterilizing device includes a heating chamber having a reservoir containing a substantially inert, vaporizable liquid having a boiling point sufficiently high to kill microorganisms unsafe for humans. The sterilizing liquid is heated to boiling by a heater submerged therein. The articles to be sterilized are placed in a perforated tray located in the chamber above the reservoir and are contacted by a blanket of substantially saturated vapors of the sterilizing liquid. A temperature controller turns the heater off and on in response to the vapor blanket rising to and falling below a predetermined level above the tray. A counter counting the number of electrical impulses or cycles thereafter transmitted to the heater turns off the heater after a predetermined number of such cycles and a fan or similar cooling apparatus is energized to cool the chamber and condense the vapors.