The structural and hydriding behaviours of the alloy LaMg11Ni after modification by mechanical grinding in tetrahydrofuran (THF) were investigated. The influence of mechanical grinding in THF on surface activation was evaluated by studying the hydrogen absorption/desorption kinetics. The alloy possesses high hydrogen storage and excellent kinetic behaviour, even at moderate temperatures. For the LaMg11Ni alloy milled in THF for 20 h, the hydrogen content of 3.4wt.% was obtained at 448 K and 3.2 MPa H2 after the initial exposure to hydrogen. An even higher hydrogen content of 3.65wt.% was obtained under the same conditions after several hydriding/ dehydriding cycles. Auger electron spectroscopy (AES) was used to determine the surface characteristics of the modified alloy. The modified alloy exhibits a rather high surface activity which improves with increase of milling time. According to XRD analysis the alloy modified by milling THF, show some degree of amorphousness.