Hydrogen absorption and desorption properties in nanocrystalline LaMg2Ni are presented. Nanostructured phases have been obtained by milling grain coarse ingot and by mechanically alloying the parent elements. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis and thermal desorption measurements. Ball milling and mechanical alloying give a significant refinement of the microstructure. Reactive milling has been used for hydrogen absorption experiments. Hydrogenation by means of reactive milling at 300 K under a pressure of 0.4 MPa leads to the formation of a stable La-hydride phase together with an amorphous phase. Thermal desorption LIP to 983 K of hydrogenated samples leads again to parent LaMg2Ni phase. (C) 2007 Elsevier Ltd. All rights reserved.