The varied emitted color of Sr3La(PO4)(3):Eu2+ phosphor was synthesized using a high temperature solid-state reaction method. The phosphor exhibits two emission bands at 418 and 500 nm corresponding to the 5d -> 4f transition of Eu2+ ions, which occupy two different crystallographic sites of Sr2+ in the Sr3La(PO4)(3) structure. With increasing the Eu2+ doping concentration, the emission color changes the cyan into the purple, and the energy transfer takes place between Eu2+ activators. The experimental results and the analysis suggest that the energy transfer mechanism should occur due to dipole-dipole interaction with an energy-transfer critical distance of 2.56 nm. When Ce3+ ions are doped together, an efficient energy transfer from Ce3+ to Eu2+ ions exists in Sr3La(PO4)(3):Ce3+, Eu2+ phosphor, the energy transfer mechanism is also d-d interaction, and the energy-transfer critical distance is 2.71 nm. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.061203jes] All rights reserved.