Abstract: A method is described for the decomposition of polymers, especially waste plastics and used plastics, in which so-called NOR--HALS compounds--that is, for example, compounds comprising the group ##STR1## in which R* is C.sub.1 -C.sub.20 alkyl, OH-substituted C.sub.1 -C.sub.20 alkyl, optionally C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.12 cycloalkyl or O- or S-interrupted C.sub.2 -C.sub.20 alkyl--are added and heating is carried out at temperatures which lie above the customary processing temperatures for polymers (280.degree. C. or more).