The first-principles calculations using full-potential in the stable F-43m phase have been performed to investigate the structural, elastic, magnetic, nature of chemical bonding and electronic properties of Fe-2-based inverse Heusler alloys. The structural stability and the lattice constants match well with the experimental results. We have further reported other mechanical, elastic and thermophysical properties for the first time of these Fe(2)NiZ (Z = Al, Si, Ga, Ge) materials. Cauchy's pressure and Pugh's index of ductility label these materials as ductile. The spin magnetic moment distributions show that these materials are ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancies in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. The charge density distribution plots present a clear picture of the stronger covalent bonding in Fe2NiSi and the decreasing trend of covalent bonding in these materials. The main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for these alloys. Spin resolved band structure calculations show that these materials are metallic in stable F-43m phase at ambient conditions. (C) 2014 Elsevier B.V. All rights reserved.