A series of Eu2+-doped and Eu2+/Mn2+-codoped Mg3(PO4)2 phosphors were synthesized by the combustion-assisted synthesis method. Under UV excitation, Mg3(PO4)2:Eu2+ presents a broad emission band, which can be decomposed into two symmetrical bands centered at λ = 427 and 467 nm, owing to the substitution of two kinds of Mg2+ sites by Eu2+ ions. In Mg3(PO4)2:Eu2+,Mn2+ phosphors, the excitation spectra monitored at the red emission of the Mn2+ ions is similar to that monitored at the blue emission of the Eu2+ ions, which illustrates the possibility of energy transfer from the Eu2+ ions to the Mn2+ ions. The variations of the emission spectra and decay lifetimes further demonstrate the existence of energy transfer from the Eu2+ ions to the Mn2+ ions under UV excitation. The energy-transfer mechanism is dominated by electric dipole-dipole interactions, which can be validated by the agreement of the critical distances obtained from the concentration-quenching (9.69 Å) and spectrum-overlap methods (8.04 Å). The 4T1 → 6A1 emission band of the Mn2+ ions in Mg3(PO4)2:0.04Eu2+, yMn2+ shows a redshift as a function of the Mn2+ concentration ( y), which has been discussed in relation to the exchange interactions between Mn2+-Mn2+ pairs. [ABSTRACT FROM AUTHOR]