A new method has been developed for the oxidation of glucose into gluconic acid over Pd/C catalysts under the room temperature and atmospheric pressure. The carbon support was prepared by the hydrothermal treatment of renewable glucose, thus contained abundant active oxygen species. The Pd/C catalyst showed high catalytic activity towards the oxidation of glucose into gluconic acid. A 100% glucose conversion and a 98% gluconic acid yield were attained within 2 h at 0.1 MPa and room temperature. Structural analysis showed that the Pd paricle sizes of the catalysts were in the range of 10.1-16.2 nm influenced by the loading of Pd. The structure/size study showed that the catalyst with optimal particle size of 10.9 nm exhibited the highest TOF (0.2388 mol(glucose) mol(Pd)/s). The catalyst showed no significant loss of activity after recycled for four times. [GRAPHICS] .