Preparation of 5-cyanovalerates (I) by the carbonylation of a 1-cyanobutene with carbon monoxide and an alkanol (II) corresponding to the ester radical at an elevated temperature and under superatmospheric pressure in the presence of a cobalt catalyst as well as in the presence of an activating solvent, in which the activating solvent used is an effective amount of a carbonic diester, a carbamate, or a urea of the general formula IIIa, IIIb, or IIIcR--O--CO--O--R (IIIa)R.sub.2 N--CO--O--R (IIIb)R.sub.2 N--CO--NR.sub.2 (IIIc)or a mixture of these compounds (R's same or different, C.sub.1 -C.sub.6 alkyl, C.sub.5 -C.sub.7 cycloalkyl groups or together form 5-membered to 7-membered rings).The end products I serve as intermediates, chiefly for the preparation of .epsilon.-caprolactam.