The present invention relates to the field of vulcanization of unsaturated polymers, in particular halogenated, and more particularly chlorinated, unsaturated polymers, such as, for example, polychloroprene, using as vulcanization agent a mixture of bis(2,5-dimercapto-1,3,4-thiadiazole) and at least one organic base. The present invention relates to the process for vulcanization of said polymers with said vulcanization mixture.