A process for hydrogenating polyenes, especially 1,5,9-cyclododecatriene, to the corresponding monoenes, especially cyclododecene, using homogeneous ruthenium catalysts comprises hydrogenating in the presence of a carboxylic acid, advantageously a C.sub.1 -C.sub.20 monocarboxylic acid, a C.sub.2 -C.sub.6 dicarboxylic acid, cyclohexylcarboxylic acid, benzoic acid, terephthalic acid, phthalic acid or phenylacetic acid, especially acetic acid, propionic acid, succinic acid or adipic acid or a C.sub.12 -C.sub.20 fatty acid. The homogeneous ruthenium catalyst is advantageously generated in situ prior to the hydrogenation. The in situ generation is carried out in the additional presence of CO or formaldehyde and the hydrogenation in the additional presence of triphenylphosphine.

Um processo para hydrogenating os polyenes, especial 1,5,9-cyclododecatriene, aos monoenes correspondentes, especial cyclododecene, usando catalizadores homogêneos do ruthenium compreende hydrogenating na presença de um ácido carboxylic, vantajosamente um C.sub.1 - C.sub.20 ácido monocarboxylic, um C.sub.2 - o ácido C.sub.6 dicarboxylic, ácido cyclohexylcarboxylic, ácido benzoic, ácido terephthalic, ácido phthalic ou o ácido phenylacetic, especial ácido acetic, ácido propionic, ácido succinic ou ácido adipic ou um C.sub.12 - ácido C.sub.20 fatty. O catalizador homogêneo do ruthenium é gerado vantajosamente no situ antes do hydrogenation. Na geração do situ é realizado na presença adicional do CO ou do formaldehyde e no hydrogenation na presença adicional do triphenylphosphine.