Nanodendritic Pd was fabricated by square-wave potential pulse (SWPP) electrolysis on Pd surface. Dendrite cell sizes and dendrite arm spacings were well below 100 nm and decreased with the increase in the frequency of SWPP. Cyclic voltammetry revealed that true surface area of Pd increased by up to 57 times by the nanodendritic structure. Nanodendritic Au was also fabricated by SWPP and its catalytic decoloration capacity was compared with that of nanoporous Au. Nanodendritic Au decomposed methyl orange more efficiently than nanoporous Au. This may be attributed to high-index facets and edges commonly found in nanodendritic structures synthesized by SWPP electrolysis.