We report here the remarkable catalytic efficiency observed for two Pd(II) azamacrocyclic complexes supported on multiwalled carbon nanotubes (MWCNTs) toward oxygen reduction reactions. Beyond a main (>90%) 4e(-) process and an onset potential close to or better than those of commercial Pt electrodes, the MWCNTs functionalization strategy, aimed at chemically defined Pd(II)-based catalytic centers, allowed the half cell to exceed the proton-exchange-membrane fuel-cell reference/target mass activity efficiency set by the U.S. Department of Energy for 2020 (440 mA/mg(PGM) at 0.9 V vs reversible hydrogen electrode).