A red-emitting LiLa2O2BO3:Sm3+,Eu3+ phosphor has been synthesized and characterized optically for white light-emitting diodes (LEDs). Because the oxyborate group (O2BO3-7) can contain high Eu3+ concentration without concentration quenching, LiLa2O2BO3 is a suitable host material for red-emitting phosphor for near-ultraviolet (n-UV) LEDs. When LiLa2O2BO3:Eu3+ was co-doped with Sm3+, emission intensity of Eu3+ was enhanced by similar to 30% than that of the sample without Sm3+ owing to the energy transfer from Sm3+ to Eu3+. This energy transfer was confirmed by faster decay times of Sm3+ as energy donors. LiLa2O2BO3:Sm3+,Eu3+ showed a relative brightness of 334.7% of that of Y2O2S:Eu3+, commercial red-emitting phosphor for n-UV LEDs. (C) 2008 The Electrochemical Society.