Crucial to enabling hydrous hydrazine as a viable fuel is the development of high-performance electrocatalysts. Herein, we report the synthesis of a palladium decorated porous nickel electrocatalyst using a combination of the dealloying and galvanic replacement methods. The obtained electrocatalyst shows outstanding catalytic activity and good long-term durability towards hydrazine oxidation. The mechanistic reason for the improved electrocatalytic performance is discussed based on the structural characterization and controlled experiments. Our study demonstrates that the electrocatalytic properties of catalyst can be improved by enhancing the number of active sites and its intrinsic activity.