In this work, we investigated the structural, electronic, elastic and thermodynamic properties of ZnNi3X (X=C, N) based on density functional theory (DFT). Our results show that the two compounds ZnNi3N and ZnNi3C are stable in nonmagnetic configuration with metallic behavior. The analysis of the phonon curves and the elastic constants predict that these compounds are thermodynamically and mechanically stable. The obtained values of Pugh’s ratio are found higher than 1.75, which means that ZnNi3X (X=C, N) are ductile and have a metallic bond, furthermore, the ZnNi3N is more affected by the temperature compared to ZnNi3C, because the lattice parameter and the Poisson’s ratio increases more rapidly in ZnNi3N than ZnNi3C. We have also studied the temperature dependent elastic constants within quasi-static approximation in the range of temperature from 0 K to 800 K. The results show that these compounds maintain their mechanical stability.