Solubilities of seven phenolic antioxidants in rubber and three antioxidants in low density polyethylene (LDPE) were measured at temperatures ranging trom 40°C–100°C. The antioxidants are more soluble in rubber than in LDPE, which is semicrystalline. The solubility of antioxidants is temperature dependent and both the melting point of the additive and its interactions with the polymer are important in determining solubility. As a general rule, solubility decreases with increasing molecular weight.