We report a solution phase synthesis of monodispersed mesoporous Pd nanoparticles (MPNs) with narrow particle size distributions. The average particle sizes can be controlled to a range of 25 nm to 42 nm, by utilizing cationic surfactants (as structure-directing agents) and triblock copolymers (as protective agents for controlled Pd deposition). The obtained MPNs exhibit very high electrocatalytic activity in formic acid oxidation.