Pt is the best catalyst for oxygen reduction reaction (ORR). It can be explained by the wellknown Sabatier Principle for catalysis: the binding energy between the reactant and the catalyst should be neither too strong nor too weak. It should be strong enough so that the bonds in the reactant are activated, but not too strong to block the subsequent desorption of products. For ORR, this principle can be expressed as a volcano curve, obtained by plotting the ORR catalytic activity against the adsorption energy of oxygenated species calculated by density functional theory (DFT). Among metal catalysts, Pt indeed occupies the central position, with moderate adsorption energy for oxygenated species and the highest catalytic activity, which is consistent with the Sabatier Principle. Much of the current search for a better catalyst for ORR, which is one of the key challenges in fuel cell technology, relies on this principle, with efforts directed at either lowering the content of the expensive Pt or finding materials with binding energy of oxygenated species close to the center of the ORR volcano curve. In contrast, Au has been cited as an example of unfavorable catalytic activity for ORR, as the adsorption energies of oxygenated species are weak, putting Au near the volcano's foothill. It explains the experimental observations that ORR on Au electrodes generally goes through the 2e - pathway, leading to the formation of H2O2 or OOH -depending on the pH, which is less efficient for producing current than the 4e -pathway on Pt catalysts. However, when the electrode potential is above 0.7 V (RHE) in alkaline solution, the ORR on Au(100) becomes a 4e -process, and in fact the current is slightly better than that on Pt(111). While this has been observed only on Au(100) within a narrow potential window (0.7~1.0 V RHE), it does fall into an important range for the optimal performance of fuel cells and pose a challenge to the Sabatier Principle and the ORR volcano plot. A number of factors have been suggested, such as the presence of either OH* or OOH*, the promotion effects of H2O solvent, or the disproportionation of HOO -. The formation of OOH* in the presence of H2O and the stability of OOH* in the presence of OH* 20 have been examined by DFT calculations. For ORR in alkaline solution, it has been suggested that the initial and the rate determining step (RDS) is an outer sphere reaction, with O2 capturing an electron from the electrode. For ORR on Au(100), such an outer sphere process has been examined systematically. Nonetheless, the overall mechanism remains unclear and disputed. It's well known that mapping out the reaction path for an electrochemical reaction is challenging, due to the complexity in the interfacial region, the dynamic nature of electrode processes in the presence of a solution layer, and the difficulties to deal with the effects of electrode potential. In recent years, it has become possible to simulate such reactions with more realistic models, including explicit solvent water molecules and DFT based AIMD (ab initio Molecular Dynamics) simulations for the solvation and entropic effects. Relevant to our current study are recent AIMD simulations of ORR reaction steps on Pt(111) in both acid and alkaline solutions. Based on the changes in the kinetics of the hydrogenation of OH* and the two competing hydrogenation channels of O* with varying electrode potential, a consistent account can be worked out for the main electrochemical observations, including the irreversible feature in the oxide region of the cyclic voltammogram, the starting potential for the decrease of ORR current, the high onset overpotential, and the shape of the polarization curve. In this paper, we report the results of AIMD simulations on the ORR mechanism on Au(100) in alkaline solution. The kinetic factors underlying the excellent performance in the 4e -ORR region are identified. The mechanism is analyzed in comparison to the ORR mechanism on Pt(111), and the j-E polarization curve is re-examined in light of these new mechanistic understandings, demonstrating how the Sabatier Principle and the ORR volcano curve are circumvented.