Vacuum ultraviolet (VUV) spectroscopic properties of undoped and Tb 3+-doped Ba 3Sc(BO 3) 3 were investigated by using synchrotron radiation. The Tb 3+-doped Ba 3Sc(BO 3) 3 sample crystallized in a flower-like shape even was synthesized at 1100 °C. Upon VUV excitation, Ba 3Sc(BO 3) 3 exhibited an intrinsic broad UV emission centered at 336 nm, which results from radiative annihilation of self-trapped exciton (STE) that may presumably be associated with band-gap excitations or molecular transitions within the BO 3 3- group. The maximum host absorption for Ba 3Sc(BO 3) 3 was found at about 180 nm. Upon doping of Tb 3+ ions into Ba 3Sc(BO 3) 3, an efficient energy transfer from the host excitations to Tb 3+via STE emission was observed, showing host sensitization of Tb 3+ occurs. The energy transfer from host to Tb 3+via STE emission in Ba 3Sc(BO 3) 3:Tb 3+ was studied as a function of temperature and Tb 3+ doping concentration. It has been demonstrated that the energy transfer efficiency was increased with either increasing temperature or Tb 3+ doping concentration. In the case of temperature dependent energy transfer, the energy transfer from the STE to Tb 3+ is thermally activated, probably due to exciton mobility, while in the case of concentration dependent energy transfer, the energy transfer from the STE to Tb 3+ is promoted due to a closer distance between the STE and Tb 3+ at high Tb 3+ concentration.