Abstract: Based on our previous work, Pd concave nanostructures with well-controlled sizes and shapes were obtained by the addition of Ru3+ during a synthetic process. The electrocatalytic oxidation of HCOOH by the four samples obtained from this synthesis was further examined. The experimental results show that by increasing the concentration of added Ru3+, the resulting Pd nanocrystals exhibit gradually improved activities in the electrocatalytic oxidation of HCOOH, which reaches the current density as high as 3507 A/g. Given the convenient synthetic method and excellent electrocatalytic performance, this series of Pd concave nanostructures could be promising candidates for commercial use.