Abstract: A heat resisting organoclay which, when incorporated to plastic compounds at high processing temperature in excess of 150° C., does not discolor the plastics, as well as a method of manufacture thereof, is provided. Antioxidant is intercalated between interlayers of the clay flakes to make a heat resistant organoclay. More specifically, antioxidant dissolved in a water-soluble organic solvent is added to a raw filter cake of organoclay for mixing. Alternatively, an aqueous solution of organic cations and antioxidants is added to a clay-water suspension. Then, they are mixed, filtered, dried and pulverized to produce a heat resistant organoclay.