A method for the production of 1, 2, 4, 5, 6, 6 - hexachlor - hexatriene - (1, 3, 5) or from 1, 2, 3, 5, 6, 6 - hexa - chlorine - hexatriene - (1, 3, 5) by dehydrochlorination of 1, 2, 3, 4, 5, 5, 6, 6 - oktachlor - hexene - (1)