The rate constants for the hydrogen donation of three 3-aryl-benzofuranone compounds with tert-butoxyl radicals have been cal-culated through laser flash photolysis (LFP) technique, which were used to evaluate the hydrogen donating abilities of those 3-aryl-benzofuranone compounds. The antioxidant activities of those 3-aryl-benzofuranone compounds in polypropylene (PP) have been studied using the oxidation induction time (OIT) of PP stabilized by those 3-aryl-benzofuranone compounds too. It has been found that the methyl group on the 2'-position can prevent the hydrogen donation of 3-aryl-benzofuranone with tert-butoxyl radicals and weakens the antioxidant activity of 3-aryl-benzofuranone in the oxidation of PP, i.e., the greater is the hydrogen do-nating ability of 3-aryl-benzofuranone with radicals, the better is the antioxidant activity of 3-aryl-benzofuranone in the oxidation of PP in the presence of oxygen.
