Chemical reactions between LiF and MgB2 with different molar ratios of 1:1 and 4:1 under hydrogen atmosphere were studied by high-pressure differential scanning calorimetry (HP-DSC) and in situ synchrotron radiation power X-ray diffraction. Hydrogen sorption properties of the composites were evaluated using a Sievert’s type apparatus. After hydrogenation only LiBH4 and MgF2 are found as the main products. However, DSC characterization showed multistep events related to LiBH4 that might be explained by different phases or some intermediates.