Energy-transfer processes from Ce3+ to Eu2+/Mn2+ and from Eu2+ to Mn2+ in host CaSiO3 are studied. Co doping Ce3+/Mn2+ or Eu2+/Mn2+ is an effective approach to enhance the orange-reddish emission of Mn2+. The ion-size compensation effect between Eu2+ and Mn2+ causes more Eu2+ to be doped into the CaSiO3 lattice, which benefits the increase of the energy transfer efficiency from Eu2+ to Mn2+. Additionally, the suitable spectrum overlapping of the Eu2+ emission to the first excited state T-4(1) of Mn2+ as well as the formation of Eu2+/Mn2+ clusters may be other causes of the enhanced Mn2+ luminescence. Eu2+/Mn2+ codoped samples can be very excited by near-UV. The excitation spectrum of Ce3+ covers a different wavelength range from that of Eu2+ (normally blue shift occurs); thus, replacement of Ce3+ for Eu2+ may make phosphors excited by shorter wavelengths. The results in this work may provide some clues for designing novel red phosphors for white-light UV light-emitting diode applications. (c) 2008 The Electrochemical Society.