The structural, elastic, and electronic properties of ReN2 are investigated by first-principles calculations with density functional theory. The obtained orthorhombic Pbcn structure is energetically the most stable structure at ambient pressure. ReN2 is a metallic, super-incompressible solid and presents a rather elastic anisotropy. The estimated Debye temperature and hardness are 735 K and 17.1 GPa, respectively. Its estimated hardness is comparative to that of Si3N4. (C) 2009 Elsevier B. V. All rights reserved.