Abstract: A moist-heat sterilization apparatus is provided which comprises a boiler shell (3), a chamber (4) inside said boiler shell (3), a heating block (14) external to said chamber (4) and in contact with the boiler shell (3), a feeding circuit (12) to supply the heating block (14) with water, and a conveying circuit (26) extending between the heating block (14) and chamber (4), the heating block (14) comprising canalization members (31) interposed between the feeding (12) and conveying (26) circuits and heating members (30) adapted to create a first steam flow through the canalization members (31). The process consists in admitting a first steam flow into a boiler shell, collecting the condensation water of the first steam flow and heating the boiler shell in such a manner that a second steam flow is produced from the condensed water.