Hydrogen is a safe renewable energy source that has a great potential to replace fossil fuels, because it is highly abundant and its oxidation product is environmentally benign. The clean way to produce hydrogen from water is to use sunlight in combination with photovoltaic cells and water electrolysis. However, the problems of transportation and storage hinders the application of hydrogen energy. The development of materials for efficient hydrogen storage remains a challenge. Several studies showed that large surface area and high pore volume are necessary to ensure high hydrogen uptake. Porous material can store hydrogen gas in the form of molecules at low temperatures and compresses hydrogen into the holes effectively. The incorporation of nanoparticles, such as hydrides or metallic alloys, to a polymer matrix may be an alternative to obtain materials with promising properties for hydrogen storage. In the present work, polymer-metal nanocomposites for hydrogen storage consisting of triblock copolymers based on styrene and butylene (such as SEBS) and a hydride-forming intermetallic compound based on LaNi5 were elaborated. Mechanical activation of the initial powder mixtures was employed to provide a good interface between the phases. A series of nanocomposites with different filler concentrations was produced and characterized by x-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and hydrogen sorption measurements. Morphological analyses showed that usually physical mixture occurred between the components and that in some cases the dispersion of the second phase must be improved as large agglomerates were observed. Hydrogen sorption tests showed an increase in the amount of hydrogen sorption in the polymer-metal nanocomposites as compared to the neat polymer matrix. Considering previous results, it is scientifically interesting and promising to continue investigation on the interaction of hydrogen with different and well-characterized polymer-based nanocomposites. Key-words: polymers, nanocomposites, metallic alloys, storage, characterization.