Abstract. Single crystals of Ba 2 NaNb 5 O 15 doped with Pr 3+ have been grown from sodium tetraborate flux. Their emission properties have been measured as a function of the doping level under different excitation and temperature conditions. The experimental observations have been accounted for by considering the effects of the crystal structure, of the doping mechanisms and of the interactions between host lattice and doping ions. The proposed conclusions have been verified by means of single crystal X-ray diffraction measurements and the resulting site occupancies of the active ions have been discussed in the light of the synthesis procedure. [6,7] have confirmed its potentialities as host lattice for laser ions. We have recently explored the visible emission properties of BNN crystals activated with Eu 3+ , Dy 3+ , Tb 3+ and Sm 3+ [8], pointing out the issues concerning the site occupancy in this host lattice and the analogies with SBN:Ln 3+ (Ln 3+ = rare earth ions). In this paper we thoroughly investigate the emission properties of Pr 3+ -doped BNN (hereafter Pr:BNN) crystals as a function of the temperature, of the doping concentration and of the excitation conditions. Our interest in this system is related to different interconnected aspects: the development of a new visible emitting material, the analysis of its excited states dynamics and of the interactions between optical centres and lattice constituents in the light of the structural properties of the host and of the Pr 3+ site occupancy, the possibility of extending the obtained information to other members of the TB niobate family, and so on.