Newly developed magnesium alloys with a consolidated nano/sub-micron structure and substantially higher specific strength may be considered as an interesting candidate for super-light high-strength applications. Consolidated nano/sub-micron structure applies to alloys with a combined microstructure of nano-crystalline and sub-micron grains. The aim of the present study was to explore the mechanical and environmental behavior of a consolidated nano/sub-micron magnesium alloy with the composition of AZ31. This was required in order to evaluate the applicability of this new structured alloy for practical applications. Although the nano/sub-micron structured alloy has more than twice the hardness and strength of the conventional alloy, its ductility and corrosion resistance were significantly lower. In addition, its stress corrosion characteristics were inferior. The significant limitation of the nanostructured alloy, in terms of ductility and corrosion performance, restricts its potential use as a structural material for practical applications.