The purpose of this communication is to compare the hydriding kinetics of bulk (250 mu m) and nano-sized (3.6 nm) palladium particles. Sorption/desorption isotherms have been measured at 25 degrees C from volumetric experiments. It is shown that nano-particles retain only some of the characteristics of bulk systems. Several major differences such as different hydrogen solubility, different magnitude of hysteresis and different plateau pressure slopes have been observed. Hydrogen sorption/desorption kinetics has been analyzed in the frequency domain. A model has been used to fit experimental impedance diagrams and determine microscopic rate-parameters in the solid solution, two-phase domain and hydride phase. It is shown that microscopic rate parameters of micro- and nano-particles do not significantly differ. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.