[en] Highlights: • Low-index surfaces of NbAl₃ have been systematically studied. • The (111) surface is the most stable stoichiometric surface. • Nonstoichiometric Al-terminated (110) surface is the most thermodynamically stable. • Surface energies and work functions of low-index surfaces have been obtained. - Abstract: The structural, electronic and surface properties of low-index surfaces of tetragonal NbAl₃ have been studied with first-principles plane-wave ultrasoft pseudo-potential method based on density functional theory. The atomic relaxations, surface energies and work functions are reported. The calculated atomic relaxations and surface energies suggest that the (111) surface is the most stable stoichiometric surface. Furthermore, the Al-terminated (110) surface is thermodynamically stable than other surfaces in both Al-rich and Nb-rich conditions.