CaS:Eu2+, CaS:Ce3+, Na+, CaS:Eu2+, Ce3+, CaS:Eu2+, Tm3+, and CaS:Eu2+, Ce3+, Tm3+ phosphors samples were prepared using a solid state chemical reaction method. Emission and excitation spectra of CaS:Eu2+ (peak emission observed at 648 nm) and CaS:Ce3+ (peak emission observed at 515 nm) were investigated. Neither Eu2+ singly doped sample nor Ce3+ and Na+ codoped sample had a long afterglow. CaS:Eu2+, Ce3+ showed some afterglow with a short persistence. By incorporation of Ce3+, an efficient energy transfer from Ce3+ to Eu2+ was found at a low doping concentration 0.1%. Emission intensity of Eu2+ was enhanced by 20%. Enhancement of long persistence of Eu2+ afterglow emission was achieved by co-doping Ce3+ in CaS:Eu2+, Tm3+ as a durable sensitizer. For the triply doped CaS:Eu2+, Tm3+, Ce3+ it was found that the persistence time was 22% longer than that of CaS:Eu2+, Tm3+. (c) 2006 The Electrochemical Society.