The structural, electronic and support effect on palladium nanoparticles (Pd NPs) prepared by sputtering deposition and chemical reduction of a Pd(II) precursor in/on a poly(ionic liquid) (PIL) was investigated in the selective hydrogenation of alpha,beta-unsaturated carbonyl compounds and dienes. Sputtering deposition generates naked NPs with a narrow size distribution (3.2-3.8 nm) that are predominantly composed of Pd(0) (85-100%). Conversely, chemical reduction produces PIL-covered NPs with almost twice the average size (6.6 nm) and only 15% Pd(0). Regard the catalytic performance, support composition (by ionic liquid (IL) addition or not) and NP location are decisive. The best activity and selectivity was obtained with imprinted Pd NPs on a PIL/IL mixture (D-MPIL.NTf2/IL-Pd catalyst). A kinetic investigation was conducted using 2-cyclohexen-1-one (CHN) and D-MPIL.NTf2/IL-Pd catalyst revealing that this reaction follows the Langmuir-Hinshelwood mechanism. Enthalpies obtaining from a Van't Hoff plot show that the adsorption of the CHN substrate on the surface of the PIL-Pd catalyst is an exothermic process (-9 kJ mol(-1)), whereas H-2 adsorption occurs by an endothermic process (12 kJ mol(-1)). This distinct behavior is consistent with the rate determining step proposed, in which the independent adsorption of reagents is followed by the hydrogenation of a pi-allyl intermediate on the catalyst surface.