Next we analyzed the influence of the thickness of the NFs in their calculated μH–composition isotherms. The isotherms for the different NF thicknesses calculated for the (001) and (111) orientations are shown on Figs. 2 and 3, respectively. Similar general trends as discussed above for the 4 nm NF can be observed. As the thickness increases, the chemical potential at which the first ‘surface’ plateau appears is practically the same; however the range of H compositions associated to this transformation (the width of the plateau) reduces as the thickness increases in correlation with the decrease of the surface to volume ratio for larger thicknesses, and tends to disappear in the bulk limit as expected. The average chemical potential at which the ‘bulk’ plateau develops increases with the NF thickness towards the bulk limiting values. The increase in the average chemical potential connected with the ‘bulk’ plateau is correlated with an average increase in the compressive pressure of the Pd atoms in the inner layers of the NF, as shown in Fig. 4 for the (111) NF at a high H/Pd concentration.