Understanding the cooperative action of palladium nanoparticles (NPs) and palladium single atoms (SAs) supported on Nis essential for developing more efficient supported transition metal catalysts. In this work, the comparison of a series of Pd-catalysts on CNTs having the same palladium loading (∼1.4 wt%) but involving different and controlled SA/NP ratios (between 2 and 200) is described. The hydrogenation of acetophenone into 1-phenylethanol and its consecutive hydrogenolysis to ethylbenzene are the chosen test reactions. Appropriate kinetic modeling of these two consecutive reactions was performed and allowed a quantitative assessment of the activity differences between catalysts as well as the demonstration of a synergy between the two palladium species (SAs and NPs). The maximum activity was clearly dependent on the distribution of the surface palladium between SAs and NPs, and interestingly, different optima for the two reactions are evidenced. This work may offer a new perspective for the design and synthesis of supported transition metal catalysts with targeted catalytic performance.