An apparatus and process for hydrogen peroxide vapor sterilization of medical instruments and similar devices make use of hydrogen peroxide vapor released from an inorganic hydrogen peroxide complex. The peroxide vapor can be released at room temperature and atmospheric pressure; however, the pressure used can be less than 50 torr and the temperature greater than 86.degree. C. to facilitate the release of hydrogen peroxide vapor. Preferred hydrogen peroxide complexes for use in the invention include Na.sub.4 P.sub.2 O.sub.7.3 H.sub.2 O.sub.2 and KH.sub.2 PO.sub.4.H.sub.2 O.sub.2. The heating rate can be greater than 5.degree. C. Optionally, a plasma can be used in conjunction with the vapor.