A nanoporous PdNi (np-PdNi) bimetallic catalyst fabricated by electrochemically dealloying a Pd20Ni80 alloy in an acid solution is reported. Residual Ni in the nanoporous alloy can be controlled by tuning dealloying potentials and the electrocatalysis of the np-PdNi shows evident dependence on Ni concentrations. With similar to 9 at.% Ni, the np-PdNi bimetallic catalyst presents superior electrocatalytic performances in methanol and formic acid electro-oxidation as well as oxygen reduction in comparison with commercial Pd/C and nanoporous Pd (np-Pd). The excellent electrocatalytic properties of the dealloyed np-PdNi bimetallic catalyst appear to arise from the combined effect of unique bicontinuous nanoporosity and bimetallic synergistic action.