Tetrahydropyridones which in one of their tautomeric forms conform to the general formula (I) ##STR1## where R.sup.1 and R.sup.2 are each independently of the other C.sub.1 -C.sub.12 -alkyl, which may be oxygen-interrupted, C.sub.5 -C.sub.6 -cycloalkyl or C.sub.7 -C.sub.12 -phenylalkyl where the phenyl is unsubstituted or monosubstituted, disubstituted or trisubstitued by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, fluorine, chlorine or bromine, or ##STR2## is a from 5- to 12-membered cycloaliphatic ring which may be monosubstituted, disubstituted, trisubstituted or tetrasubstituted by C.sub.1 -C.sub.4 -alkyl, andR.sup.3 is hydrogen, substituted or unsubstituted alkyl or phenyl alkyl or alkanoyl, are effective stabilizers for plastics and coatings.