Structural, energetic and electronic properties of the low-index B2O3 surfaces (1 0 1), , (1 0 0) and (0 0 1) were studied theoretically at density-functional level. A composition scheme was developed for slab models of the surfaces. It was found that the surface stability decreases in the order , in line with the number of unsaturated bonds per surface area. All surfaces reconstruct in order to increase the average coordination number of atoms in the upper layers. For the surface, a first step toward a phase transition was observed. Occupied surface states were found 0.1 eV above the valence band for the most stable (1 0 1) surface.