Pyrroles of the formula (I) are prepared by dehydrogenating pyrrolidines of the formula (II) where R1 and R2, independently of one another, are hydrogen or an aliphatic radical of 1 to 6 carbon atoms, or pyridines of the formula (III) are prepared by dehydrogenating piperidines of the formula (IV) where R3, R4 and R5, independently of one another, are hydrogen or an aliphatic radical of 1 to 6 carbon atoms, in the presence of a supported noble metal catalyst, by a process in which the dehydrogenation is carried out in the presence of from 1 to 50% by weight, based on the pyrrolidine or piperidine and water, of water.