The Au electrode plated nanostructure Pd was used to study the reaction mechanism of C.I. reactive blue 19 and reactive brilliant blue K-GR with atomic hydrogen in 0.2M H2SO4 solution by the electrochemical method. The nanostructured Pd/Au electrode showed the various forms of hydrogen. Through the result of cyclic voltammetry, Tafel curve and EIS, the protonation of dye molecule could accelerate the production of atomic hydrogen and the adsorption of dye on Pd/Au electrode. The decolorization efficiency using potentiostatic polarization at -0.18V was highest than that at other polarization potential because the proportion between adsorbed dye and adsorbed atomic hydrogen on electode was optimum.