Abstract: A process of the microbiological preparation of 1,3 propane diol from glycerol in growth media of suitable bacterial strains is described, accompanied by the addition of a cosubstrate in the form of a H-donor and the separation of the propane diol formed. It is characterized in that a) biomass is formed in a growth phase from the selected bacterial strain and accompanied by feeding with glycerol and, if necessary, while substantially excluding the H-donor until a stationary growth phase occurs and b) further glycerol and H-donor matched to the biomass are added to the resulting stationary cell suspension for increased 1,3-propane diol formation. This process makes it possible to produce 1,3-propane diol in a high yield from glycerol with a small amount of unobjectionable by-products in a batchwise manner or in continuous form, following immobilization.