Structural, elastic and electronic band structure properties of A-15 type Nb-based intermetallic compounds Nb 3 B (B = Os, Pt, Au) have been revisited using first principles calculations based on the density functional theory (DFT). All these show excellent agreement with previous reports. More importantly, electronic bonding, charge density distribution and Fermi surface features have been studied in detail for the first time. Vickers hardness of these compounds is also studied. The Fermi surfaces of Nb 3 B contain both holeand electron-like sheets, the features of which change systematically as one move from Os to Au. The electronic charge density distribution implies that Nb 3 Os, Nb 3 Pt and Nb 3 Au have a mixture of ionic and covalent bondings with a substantial metallic contribution. The charge transfer between the atomic species in these compounds has been explained via the Mulliken bond population analysis and the Hirshfeld population analysis. The bonding properties show a good correspondence to the electronic band structure derived electronic density of states (DOS) near the Fermi level. Debye temperature of Nb 3 B (B = Os, Pt, Au) have been estimated from the elastic constants and show a systematic behavior as a function of the B atomic species. We have discussed implications of the results obtained in this study in details in this paper.