Hydrogen desorption from R2Fe17Hx, (R=Nd and Dy) compounds with x <= 5 has been studied using differential scanning calorimetry (DSC). Overall hydrogen binding energies are very similar in both systems regardless their different crystal structures. The heat of hydrogen desorption is 29.2 +/- 0.8 kJ mol H-1 for both R2Fe17Hx family compounds. Desorption activation energies are also very close: 78 +/- 8 kJ and 79 +/- 4 kJ mol H-1 for Nd and Dy-containing compounds, respectively. The rare earth nature modifies however the local interaction between hydrogen and the intermetallic compound. For Nd, H-atoms occupy two non-equivalent and well-defined energy sites whereas a unique energy site with a broad energy distribution is detected for Dy. This peculiar behavior is discussed in terms of the different structural properties of the light (Nd) and heavy (Dy) rare-earth R2Fe17 compounds. (C) 2013 Elsevier B.V. All rights reserved.