The invention relates to a method for producing macrocyclic ketones of general formula (I) by direct cyclisation of compounds of general formula (II) in the gas phase on a heterogeneous catalyst. In general formula (I), X represents a monounsaturated or polyunsaturated or saturated C.sub.10 C.sub.17 alkyl radical which can be optionally substituted by a C.sub.1 C.sub.6 alkyl radical, and in general formula (II), R.sub.1, R.sub.2 can respectively be the same or different and represent hydrogen or C.sub.1 C.sub.6 alkyl, and has the above-mentioned designation. ##STR00001##