First principle calculations have been carried out to study energetic of boron atom impurities in bulk and symmetric Sigma 5(310) tilt grain boundaries of the ordered stoechiometric B2 FeAl intermetallic. A set of configurations was considered for studying the bulk behaviour: B in tetrahedral and octahedral interstitial positions or substituting Al and Fe. For the analysis of the segregation at the grain boundary, calculations were done for B substituting Al and Fe at three different locations and for B filling empty spaces along the interface. In each case, the defect formation energies were calculated to determine the site preference and their relative stability. The results indicate that B doping is metastable in the bulk and tends to segregate along the grain boundary. The overall behaviour of the B atoms at the boundary is essentially driven by the strong Fe-B interactions.