The present invention relates to a gentle process for catalytic hydrogenation and to a process for the preparation of biotin using the hydrogenation step. The process according to the invention for the selective, catalytic hydrogenation of a C--C double bond on a thiazole ring system having at least one functional group which can be converted into a salt under basic conditions is characterised in that the hydrogenation is carried out in a protic solvent is a pH>7.
