Hydrogen generation via hydrolysis of 250 mg hydrogenated Mg(3)La and La(2)Mg(17) in 100 ml water has been investigated at 298 K. Hydrolysis reactions of hydrogenated Mg(3)La and La(2)Mg(17) obtained by induction melting and then hydrogenated at 298 K is found to be fast when they are immersed in water. The hydrolysis reaction of hydrogenated Mg(3)La almost completes within 21 min with faster kinetics and higher yield than those obtained of hydrogenated La(2)Mg(17). The hydrogen production rate is 43.8 ml min(-1) g(-1) of hydrogen in the first 20 min of reaction compared to a conversion yield of 88% for hydrogenated Mg(3)La and 40.1 ml min(-1) g(-1) of hydrogen in the first 20 min of reaction for hydrogenated La2Mg17. It is related to the catalytic effect of LaH(3) formed during the hydriding process, accentuating corrosion of MgH(2) greatly. The experimental curves of hydrogen generation kinetics at room temperature are well fitted by the Avrami-Erofeev equation. The reaction mechanism of hydrogenated Mg(3)La and La(2)Mg(17) was also discussed. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.