Magnesium was milled under hydrogen with three types of carbon allotropes: carbon black, graphite, and multi-walled carbon nanotubes, respectively, using a special low-energy shearing mill. Structural and phase evolution were investigated using X-ray diffractometry (XRD) and morphology was investigated by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). Raman spectroscopy was used to investigate the changes in the nature of carboncarbon bonding and differential scanning calorimetry (DSC) to investigate desorption characteristics. A Sieverts-type apparatus was applied to characterize the hydrogen absorption and desorption properties. It was found that graphite not only improved the hydrogen absorption, but also the desorption kinetics.