We present first-principles calculations of the structural and electronic properties of binary GaN, ScN and Sc x Ga 1−x N alloys in the zinc-blende structure using pseudopotential plane-wave method within the density functional theory. The alloys are described by considering configurations in 16-atom supercells, corresponding to 2 × 2 × 2 conventional cubic cells. The lattice parameter, bulk modulus, bulk modulus derivation, the energy band gap and bowing parameter are obtained as a function of Sc concentration for ternary alloys Sc x Ga 1−x N . Our studies focus on the concentration dependence of the electronic band structure and bowing parameter of these alloys. We found that x composition affects strongly bowing parameter and the band gap increases with increasing Sc concentration for Sc x Ga 1−x N in the zinc-blende structure. The results also show that the energy band gap and bowing parameter of the Sc x Ga 1−x N alloys can be obtained by a third-order polynomial equation, E gap (x) = −2.56x 3 + 4.29714x 2 − 0.94857x + 1.83429 eV and b(x) = −72.61x 3 + 117.7x 2 − 70.27x + 16.08 eV, respectively.