The preparation of benzoic acid-functionalized CaF2:Ln(3+) (Ln = Eu or Tb) nanoparticles and their sensitized luminescence are described in this report. First, to achieve sufficient proof for energy transfer from benzoic acid (BA) to lanthanide ions doped in nanoparticles, weemploy Eu3+ as the microscopic probe and investigate the luminescent spectra of benzoic acid-functionalized CaF2:Eu3+ (BA-CaF2:Eu3+) nanoparticles. Next, to further reveal the difference between sensitized luminescence and common luminescence for Eu3+ doped in CaF2 nanoparticles, we study the emission spectra of BA-CaF2:Eu3+ nanoparticles excited at 286 nm and 397 nm, respectively. Finally, we analyze and compare the luminescent spectra of BA-CaF2: Tb3+ and CaF2:Ce3+, Tb3+ nanoparticles in detail. Our results indicate that both Eu3+ and Tb3+ doped in CaF2 nanoparticles can be efficiently sensitized through benzoic acid. (C) 2011 Elsevier B.V. All rights reserved.