An apparatus for sterilizing instruments at atmospheric pressure is provided. The apparatus includes a receiver, a sterilant reservoir, a rinsant reservoir, a waste reservoir, a microwave source, and a controller. The receiver receives the instruments to be sterilized and is made of a non-microwave absorptive material. The sterilant reservoir contains a sterilant fluid that is absorptive of microwave energy and has a boiling point greater than 100° Celsius. The rinsant reservoir contains a chemical rinsant fluid that is capable of solvating or displacing the sterilant fluid and does not support microbial viability or growth. The microwave source is positioned with respect to receiver so as to emit microwave energy into the receiver. The reservoirs are each in selective fluid communication with the receiver and the controller selectively moves the sterilant fluid or the chemical rinsant fluid from the reservoirs to the receiver and from the receiver to the waste reservoir.
