First-principles calculations within density functional theory (DFT) with the projector augmented wave (PAW) technique were used to investigate the stabilities of intermetallics in the Au-Rb system at 0 K. Four intermetallics: Au 7 Rb 3 , Au 3 Rb 2 , Au 5 Rb and AuRb were investigated in their observed experimental structures. The Au 2 Rb compound, reported in the Au-Rb phase diagrams without specifying explicitly its structure, was also investigated by inspecting several hypothetical structures. A suspect compound (AuRb 2 ) was also investigated. Results show that: (i) The Au 3 Rb 2 and Au 7 Rb 3 compounds, which were never reported in any Au-Rb phase diagram, are stable at 0 K. (ii) The Au 2 Rb compound is not a ground state for all the tested structures. (iii) Stability of the Au 5 Rb and AuRb compounds was confirmed. (iv) The new compound AuRb 2 , not yet reported experimentally, is found mechanically stable at 0 K.