We report intense green luminescence upon blue light excitation in Eu2+-activated Ca8Zn(SiO4)(4)Cl-2 prepared by high temperature solid state reaction with nominal composition of (2 - x)CaO-xZnO-SiO2-CaCl2 (0 <= x <= 1.1). It is observed that the material phase gradually converts from Ca3SiO4Cl2:Eu2+ to Ca8Zn(SiO4)(4)Cl-2:Eu2+ followed by improved luminescent properties with increasing x. The two phosphors both emit with a maximum at 505 nm. Significantly, Ca8Zn(SiO4)(4)Cl-2:Eu2+ shows a more intense excitation band in the blue centered at 450 nm. Upon 450 nm excitation, the integrated emission intensity of Ca8Zn(SiO4)(4)Cl-2: Eu2+ is 1.3 times stronger Ca8Mg(SiO4)(4)Cl-2:Eu2+ and nearly the same as Ca3Sc2Si3O12:Ce3+ phosphors. Attempts to understand the origins of the intense luminescence are presented on the basis of diffuse reflection spectra and fluorescence decays of Ca8Zn(SiO4)(4)Cl-2:Eu2+ in comparison with related phosphors. The present results suggest that Ca8Zn(SiO4)(4)Cl-2:Eu2+ could be a promising green emitting phosphor for excitation by blue light emitting diodes. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3518763] All rights reserved.