An apparatus (200, 300, 400) for generating superheated steam capable of reducing or eliminating microorganisms associated with an item (230) includes a gas heater (10) for heating a gas, a steam generator coupled to the gas heater (10) and having a reservoir (216, 304) for supplying water, wherein the heater (10) heats the gas such that when water is combined therewith, a mixture of superheated steam and gas capable of reducing or eliminating microorganisms is discharged from the apparatus (200, 300, 400). The generation of the steam-gas mixture may be done at one atmosphere of pressure and the mixing may be done prior to expelling the fluid from the apparatus (200, 300, 400). The apparatus (400) may be configured as a hand-held device, A method of treating an item (230) for microorganisms includes generating a superheated steam at approximately one atmosphere of pressure, directing a flow of the steam onto the item (230), and reducing or eliminating microorganisms using the steam.