A dehydrocyclization process is described for producing polynuclear organic compounds by contacting a starting organic material having at least one ring moiety comprising at least two adjacent ring carbon atoms each bonded to an independently selected monovalent radical comprising at most about eight carbon atoms provided at least one of the monovalent hydrocarbon radicals comprises more than one carbon atom with a crystalline copper aluminum borate catalyst. The preferred catalyst comprises at least one member selected from the group consisting of (a) crystalline copper aluminum borate and (b) zero valent copper on a support comprising at least one member selected from the group consisting of Al.sub.4 B.sub.2 O.sub.9 and the crystalline copper aluminum borate, the zero valent copper on the support being formed by the reduction of the crystalline copper aluminum borate. The process is conducted under conditions sufficient to effect cyclization between (i) a carbon atom of one of the radicals and (ii) a carbon atom of the other radical forming a dehydrocyclization product comprising a polynuclear compound wherein the new ring comprises at least 5 carbon atoms.