Twelve different compositions of the ternary Nb–Ni–Si system were synthesized and heat-treated at 1073 K for up to 1000 h. The microstructure of the samples were analyzed using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and X-ray Diffraction. The results from this work solve inconsistencies between the existing experimental information and the new computational predictions, in favor of the latter, due to the difficulty of reaching thermal equilibrium at this temperature.