Through a citric acid assisted hydrothermal method, the RE3+ (RE3+ = Ce3+, Tb3+) doped cubic phase BaGdF5 nanocrystals with a sphere-like morphology and an average size of 30 nm have been synthesized. The samples show paramagnetic properties at 300 K. The photoluminescence spectra of the obtained samples suggest that the existence of Ce3+ can dramatically enhance the emission intensity of Tb3+ due to an efficient energy transfer from Ce3+ to Tb3+. The energy transfer efficiency from Ce3+ to Tb3+, the critical energy transfer distance between Ce3+ and Tb3+, and the energy transfer mechanism of Ce3+-Tb3+ are discussed based on the experimental data and the theoretical analysis. (C) 2012 Elsevier Ltd. All rights reserved.