Abstract: A double-walled steam oven is disclosed wherein an outer oven wall surrounds, and is spaced from an inner oven wall, the inner oven wall defining a heating or sterilization chamber. The heating chamber includes a rack or other support for receiving articles to be steam heated or sterilized. A hot water tank is provided at the bottom of the inner oven, where steam is generated by a suitable heater. The steam rises through the inner oven, and exits therefrom at the top wall thereof into the outer oven. The exiting steam is then forced downwardly around the exterior of the walls of the inner oven and exits from the outer oven near the bottom. Condensate formed on the outer wall of the outer oven drains down to the bottom of the oven into a return water tank, from which it flows back to the heater tank in the inner oven.