Low temperature curing of elastomer

A process for low temperature curing of an external cable jacket of a compounded polychloroprene rubber on the exterior of a composite cable that includes thermoplastic materials, said process comprising adding to polychloroprene rubber an amount of a curing system which comprises a vulcanizing agent selected from the group consisting of magnesium oxide-zinc oxide and lead oxide with a 90:10 to 10:90 parts by weight mixture of N,N'-diethylthiourea and the di-ortho-tolylguanadine salt of dicatechol borate and thereafter heating said rubber composition at a temperature of from 200.degree.-300.degree. F. for from 0.1 to 5 minutes at a pressure of from 3-10 atmospheres to effect the cure.