Abstract: A process and an installation for utilizing organic substances are proposed, in which the substances are correspondingly comminuted and processed by mixing and reaction stages to utilizable compost.The installation essentially comprises a heatable fermenter with a stirrer located therein. In order to obtain an approximately closed process circuit the comminuted substances are supplied as so-called fresh material by a supply shaft to a conveying shaft constructed as a heat exchanger and undergo corresponding heating therein. Through further supply of fresh material the already heated fresh material is supplied to the fermenter and mixed therein by the stirrer accompanied by further heating.The fermented matter formed in the fermenter, on supplying further fresh material, can be admixed in a specific ratio as so-called bacterial inoculum with the fresh material throughout the process circuit.