A process for preparing sebacic acid by reacting in a first step (i) linoleic acid with water catalyzed by an oleate hydratase to form 10-hydroxy-12-octadecenoic acid, in a second step (ii) pyrolysing the 10-hydroxy-12-octadecenoic acid to 1-octene and 10-oxo-decanoic acid and in a third step (iii) oxidizing the 10-oxo-decanoic acid to sebacic acid.