PURPOSE: To obtain new tetramethylpiperidine compounds suitable to use as light stabilizers, heat stabilizers, or oxidation stabilizers for organic materials.

CONSTITUTION: The compound of formula I [R1 is an alkyl, O, OH, CH2CN, alkoxy, alkenyl, phenylalkyl or the like; R2 and R3 are each an alkylene; R4 is CO, COCO or COCH2CO; (n) is 1-4; R5 is an alkyl, alkenyl, phenylalkyl, tetrahydrofurfuryl or the like at n=1, alkylene, 2-hydroxytrimethylene, phenylenedimethylene, CO-R12-CO (R12 is direct bond, alkylene, cyclohexylene, phenylene or the like at n=2, aliphatic 4-18C triacyl, aromatic 9-18C triacyl or the like at n=3; aliphatic 6-18C tetraacyl, aromatic 10-18C tetraacyl or the like at n=4], for example, the compound of formula II, is obtained by reacting a compound of formula III with a suitable alkylation or acylation agent at a suitable molar ratio.