The synthesis of the (rocksalt phase) single-crystal square-like cross-sectional MgS nanotubes via a thermal reaction process was reported for the first time in the family of II–VI sulfide semiconductors, which enriches the wide spectrum of diverse inorganic nanotubular structures. As-grown MgS nanotubes are structurally uniform single-crystals; an individual faceted tube is enclosed by four {020} crystal planes and grows along the [001] orientation. The MgS nanotubes exhibited efficient hydrogenstorage capacity of � 2.2 wt% at room temperature under hydrogen pressure of 33.6 atm and one intensive cathodoluminescence emission band centered at � 688 nm. The new concept established here will be very helpful in developing other types of Mg-based material nanotubes with high a hydrogenstorage capacity. Moreover, the MgS nanotubes’ cavity could be filled with different semiconducting materials with various band gaps to give interesting electrical and optical nanodevices.