<p>A cold sterilizer comprises a tray for containing a sterilant and instruments to be sterilized, a lid fitting over the tray, a timer for measuring the period for which the instruments are to be contained in the sterilant to effect sterilization and means for resetting the timer to its original setting for a sterilization upon lifting the lid from the tray during the sterilization. The sterilizer may further comprise means for locking the lid onto the tray and means operatively connecting the timer to the locking means so that the locking means is locked while the timer is timing a sterilization and the locking means unlocks when the period for which the timer is set has expired. There may also be provided means for manually overriding the timer and unlocking the locking means during a sterilization and for thereupon resetting the timer to its original setting for the sterilization.</p>
