A process for treating used absorbent sanitary products, comprising the steps of: - providing a rotary cylindrical autoclave having an inner surface (22) and two ends, at least one of which terminates in a hatch (18, 20) that can be opened to enable access to said autoclave (14) and sealably closed to enable pressurization of said autoclave (14)； - loading said autoclave (14) with closed absorbent sanitary products； - heating and pressurizing the autoclave (14) to a sterilization temperature and at the same time driving the autoclave (14) in rotation about a longitudinal axis (A) thereof, wherein said step of heating and pressurizing the autoclave (14) envisages a first temperature regime for the products contained in the autoclave and a second temperature regime, higher than the first temperature regime, for said inner surface (22).
