The viscoelastic properties and stabilities of those properties of organic hybrids consisting of chlorinated polyethylene (CPE) and tetrakis [methylene-3-(3-5-di-tert-butyl-4-hydroxy phenyl)propionyloxy]methane (AO-60) and triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methyl phenyl)propionyloxy] (AO-70) were investigated. The CPE/AO-70 hybrids show only one transition, whereas for the CPE/AO-60 hybrids, one novel relaxation appears above the glass-transition temperature of CPE. This relaxation on the higher temperature side in the mechanical spectrum for CPE/AO-60 is associated with the appearance of the AO-60-rich phase. Furthermore, the stabilities of the viscoelastic properties and microstructures of the organic hybrids consisting of CPE and multifunctional hindered phenols are dominated by the strength of the intermolecular interaction between CPE and phenols and the conformations of the middle skeletal parts of hindered phenols.