A new working solution consisting of 2-pentylanthraquinone (PAQ) and 6-pentyl-1,2,3,4-tetrahydroantraquinone (4HPAQ) was hydrogenated and then oxidized by O-2 to produce H2O2. The oxidation reaction was conducted in a well-stirred batch reactor at 30similar to50degreesC and 0.10similar to0.20 MPa. By measuring the concentrations of generated H2O2 by iodometry, the intrinsic kinetics for the gas-liquid oxidation of 6-pentyl-1,2,3,4-tetra-hydroanthacene-9,10-diol (4HPAQH(2), the only hydrogenated product in the hydrogenated working solution) with molecular oxygen were studied. An exponential model was employed to describe the reaction rate and the kinetic parameters were obtained. The results show that the reaction rate is 0.7 and 1.4 order in the concentration of 4HPAQH(2) and oxygen pressure, respectively, and the activation energy for oxidation is 41.3 kJ/mol.