A series of new luminescence emission-tunable phosphors KCaY(PO4)(2): 0.03Ce(3+), yTb(3+) have been synthesized by high temperature solid-state reaction method. Under ultraviolet light excitation, KCaY(PO4)(2): 0.03Ce(3+), yTb(3+) can achieve tunable emission from deep blue to yellowish-green by changing the concentration of Tb3+. The efficient energy transfer process from Ce3+ to Tb3+ ions was observed and confirmed in terms of corresponding excitation, emission spectra and photoluminescence decay curves, which the efficiency is above 80%. In addition, the energy transfer mechanism from Ce3+ to Tb3+ was proved to be dipole-dipole interaction in KCaY(PO4)(2) host. By utilizing the principle of energy transfer and appropriate tuning of Ce3+/Tb3+ contents, KCaY(PO4)(2): 0.03Ce(3+), yTb(3+) can realize emission color tunable and have potential application as an UV-convertible phosphor in white light-emitting diodes. (C) 2013 Elsevier Ltd. All rights reserved.