The first-principles study on the mechanical stability, elastic and thermodynamic properties of WN(2) with P6(3)/mmc and P-6m2 phases are reported using the pseudopotential plane wave method within the generalized gradient approximation. The calculated equilibrium parameters are in good agreement with the available theoretical data. A complete elastic tensor and crystal anisotropies of the ultra-incompressible WN(2) are determined in the wide pressure range. By the elastic stability criteria, it is predicted that P6(3)/mmc and P-6m2 phases in WN(2) are not stable above 175.1 GPa and 170.1 GPa, respectively. Finally, by using the quasi-harmonic Debye model, the bulk modulus, relative volume, the coefficient of thermal expansion, and the Gruneisen parameter of WN(2) are also successfully obtained in the present work. (C) 2011 Elsevier B.V. All rights reserved.